From 62fe1409c695b0247453971835ddf8a3225c5996 Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Wed, 30 Sep 2020 18:52:58 -0400
Subject: [PATCH 01/32] kernel-builder: Rework its ergonomics

---
 overlay/mobile-nixos/kernel/builder.nix     | 141 +++++++++++++++-----
 overlay/mobile-nixos/kernel/compiler-gcc6.h |  69 ++++++++++
 2 files changed, 173 insertions(+), 37 deletions(-)
 create mode 100644 overlay/mobile-nixos/kernel/compiler-gcc6.h

diff --git a/overlay/mobile-nixos/kernel/builder.nix b/overlay/mobile-nixos/kernel/builder.nix
index a6d4ccb43..ddc8d8a3e 100644
--- a/overlay/mobile-nixos/kernel/builder.nix
+++ b/overlay/mobile-nixos/kernel/builder.nix
@@ -12,6 +12,8 @@
 # It is also an experiments ground for a more ergonomic interface.
 #
 
+# This is the callPackage signature.
+# These are dependencies for dependency injection.
 { stdenv
 , path
 , buildPackages
@@ -27,6 +29,7 @@
 , gmp
 , libmpc
 , mpfr
+, dtc
 
 , libelf
 , utillinux
@@ -41,42 +44,59 @@
 }:
 
 let
-  # FIXME : implement some basic rules for most version strings.
+  # For now this is a no-op.
   modDirify = v: v;
+
+  # Shortcuts
+  inherit (stdenv.lib) optionals optional optionalString;
+  inherit (stdenv.hostPlatform) platform;
+
+  maybeString = str: optionalString (str != null) str;
 in
 
+# This is the builder function signature.
+
+# We have to be provided with a source
 { src
+# And a version
 , version
 , modDirVersion ? modDirify version
 
+# Additionally, a config file is required.
 , configfile
-, hasDTB ? false
 
-, kernelPatches ? []
+# Togglable common quirks
+, enableCenteredLinuxLogo ? true
+, enableLinuxLogoReplacement ? true
+, linuxLogo224PPMFile ? ./logo_linux_clut224.ppm
+, enableRemovingWerror ? false
+, enableCompilerGcc6Quirk ? false
+
+# Usual stdenv arguments we are also setting.
+# Use the ones given by the user for composition.
+, nativeBuildInputs ? []
 , patches ? []
-, postPatch ? ""
 , makeFlags ? []
-, nativeBuildInputs ? []
+, prePatch ? null
+, postPatch ? null
+, postInstall ? null
 
 # Part of the "API" of the kernel builder.
 # Image builders expect this attribute to know where to find the kernel file.
+# XXX : review if we can detect this instead in a safe manner
 , file ? stdenv.hostPlatform.platform.kernelTarget
 
-# FIXME : useful?
-, isModular ? true
+# Part of the usual NixOS kernel builder API
 , installsFirmware ? true
+, isModular ? true
+, kernelPatches ? []
 
-}:
+, ...
+} @ inputArgs:
 
 let
-  commonMakeFlags = [
-    "O=$(buildRoot)"
-  ]
-  ++ stdenv.lib.optionals (stdenv.hostPlatform.platform ? kernelMakeFlags) stdenv.hostPlatform.platform.kernelMakeFlags
-  ;
-
   # Path within <nixpkgs> to refer to the kernel build system's file.
-  nixosPath = "${path}/pkgs/os-specific/linux/kernel/";
+  nixosKernelPath = "${path}/pkgs/os-specific/linux/kernel/";
 
   # Same installer as in <nixpkgs>, though they don't expose it :/.
   installkernel = writeTextFile {
@@ -92,17 +112,19 @@ let
 
   # Inspired from #91991
   # https://github.com/NixOS/nixpkgs/pull/91991
+  # (required for menuconfig)
   pkgconfig-helper = writeShellScriptBin "pkg-config" ''
     exec ${buildPackages.pkgconfig}/bin/${buildPackages.pkgconfig.targetPrefix}pkg-config "$@"
   '';
 
-  # Shortcuts
-  inherit (stdenv.lib) optionals optional optionalString;
-  inherit (stdenv.hostPlatform) platform;
+  hasDTB = stdenv.hostPlatform.platform.kernelDTB;
 in
 
-# We'll append to this derivation inside passthru.
-let kernel = stdenv.mkDerivation {
+# This `let` block allows us to have a self-reference to this derivation.
+# We'll re-use this derivation inside passthru for normalizedConfig and menuconfig.
+let kernelDerivation =
+
+stdenv.mkDerivation (inputArgs // {
   pname = "linux";
   inherit src version file;
 
@@ -116,13 +138,16 @@ let kernel = stdenv.mkDerivation {
     ++ optional (stdenv.lib.versionAtLeast version "4.14") libelf
     ++ optional (stdenv.lib.versionAtLeast version "4.15") utillinux
     ++ optionals (stdenv.lib.versionAtLeast version "4.16") [ bison flex ]
+    # Mobile NixOS inputs.
+    # While some kernels might not need those, most will.
+    ++ [ dtc ] 
     ++ nativeBuildInputs
   ;
 
   patches =
     map (p: p.patch) kernelPatches
     # Required for deterministic builds along with some postPatch magic.
-    ++ optional (stdenv.lib.versionAtLeast version "4.13") "${nixosPath}/randstruct-provide-seed.patch"
+    ++ optional (stdenv.lib.versionAtLeast version "4.13") "${nixosKernelPath}/randstruct-provide-seed.patch"
     ++ patches
   ;
 
@@ -135,9 +160,12 @@ let kernel = stdenv.mkDerivation {
     if [ -e scripts/ld-version.sh ]; then
       sed -i scripts/ld-version.sh -e "s|/usr/bin/awk|${buildPackages.gawk}/bin/awk|"
     fi
-  '';
+  ''
+    + maybeString prePatch
+  ;
 
   postPatch = ''
+    echo ":: Patching for reproducibility"
     # Set randstruct seed to a deterministic but diversified value. Note:
     # we could have instead patched gen-random-seed.sh to take input from
     # the buildFlags, but that would require also patching the kernel's
@@ -149,27 +177,55 @@ let kernel = stdenv.mkDerivation {
         $(echo ${src} ${configfile} | sha256sum | cut -d ' ' -f 1 | tr -d '\n')
     fi
 
-    # FIXME : make optional...
+    echo ":: Removing default OEM-provided certificates"
+    rm -vf *.x509
+
+    echo ":: Patching tools/ shebangs"
+    patchShebangs tools
+
+  '' + optionalString enableLinuxLogoReplacement ''
+    echo ":: Replacing the logo"
+    cp ${linuxLogo224PPMFile} drivers/video/logo/logo_linux_clut224.ppm
+
+  '' + optionalString enableCenteredLinuxLogo ''
     # Makes the "logo" option show only one logo and not dependent on cores.
     # This should be "safer" than a patch on a greater range of kernel versions.
     # Also defaults to centering when possible.
     
+    echo ":: Patching for centered linux logo"
     if [ -e drivers/video/fbdev/core/fbmem.c ]; then
+      # Force showing only one logo
       sed -i -e 's/num_online_cpus()/1/g' \
         drivers/video/fbdev/core/fbmem.c
+
+      # Force centering logo
       sed -i -e '/^bool fb_center_logo/ s/;/ = true;/' \
         drivers/video/fbdev/core/fbmem.c
     fi
+
     if [ -e drivers/video/fbmem.c ]; then
+      # Force showing only one logo
       sed -i -e 's/num_online_cpus()/1/g' \
         drivers/video/fbmem.c
     fi
 
-    # Overrides the kernel logo
-    cp ${./logo_linux_clut224.ppm} drivers/video/logo/logo_linux_clut224.ppm
+  '' + optionalString enableRemovingWerror ''
+    echo ":: Removing all -Werror from makefiles"
+    (
+    for i in $(find . -type f -name Makefile) $(find . -type f -name Kbuild); do
+      sed -i 's/-Werror-/-W/g' "$i"
+      sed -i 's/-Werror=/-W/g' "$i"
+      sed -i 's/-Werror//g' "$i"
+    done
+    )
 
-    ${postPatch}
-  '';
+  '' + optionalString enableCompilerGcc6Quirk ''
+    echo ":: Adding GCC6 compiler compatibility shim"
+    cp -v "${./compiler-gcc6.h}" "./include/linux/compiler-gcc6.h"
+
+  ''
+    + maybeString postPatch
+  ;
 
   configurePhase = ''
     runHook preConfigure
@@ -229,7 +285,8 @@ let kernel = stdenv.mkDerivation {
       exit 1
     fi
   
-    # Note: we can get rid of this once http://permalink.gmane.org/gmane.linux.kbuild.devel/13800 is merged.
+    # We have to keep this around, even when Linux supports this in mainline, as kernel forks might
+    # be older than the mainline fix.
     buildFlagsArray+=("KBUILD_BUILD_TIMESTAMP=$(date -u -d @$SOURCE_DATE_EPOCH)")
 
     cd $buildRoot
@@ -258,25 +315,34 @@ let kernel = stdenv.mkDerivation {
     mkdir -p $out/dtbs/
     make $makeFlags "''${makeFlagsArray[@]}" dtbs dtbs_install INSTALL_DTBS_PATH=$out/dtbs
   ''
+    + maybeString postInstall
   ;
 
   hardeningDisable = [ "bindnow" "format" "fortify" "stackprotector" "pic" "pie" ];
 
-  # Absolute paths for compilers avoid any PATH-clobbering issues.
-  makeFlags = commonMakeFlags ++ [
+  makeFlags = [
+    "O=$(buildRoot)"
     "CC=${stdenv.cc}/bin/${stdenv.cc.targetPrefix}cc"
     "HOSTCC=${buildPackages.stdenv.cc}/bin/${buildPackages.stdenv.cc.targetPrefix}cc"
     "ARCH=${stdenv.hostPlatform.platform.kernelArch}"
-  ] ++ stdenv.lib.optional (stdenv.hostPlatform != stdenv.buildPlatform) [
-    "CROSS_COMPILE=${stdenv.cc.targetPrefix}"
-  ] ++ makeFlags;
+    "DTC_EXT=${buildPackages.dtc}/bin/dtc"
+  ]
+  # Use platform-specific flags
+  ++ stdenv.lib.optionals (stdenv.hostPlatform.platform ? kernelMakeFlags) stdenv.hostPlatform.platform.kernelMakeFlags
+  # Mark as cross-compilation
+  ++ stdenv.lib.optional (stdenv.hostPlatform != stdenv.buildPlatform) [ "CROSS_COMPILE=${stdenv.cc.targetPrefix}" ]
+  # User-provided makeFlags
+  ++ makeFlags
+  ;
+
 
   requiredSystemFeatures = [ "big-parallel" ];
   enableParallelBuilding = true;
   dontStrip = true;
 
+  # {{{
   passthru = {
-    normalizedConfig = kernel.overrideAttrs({ ... }: {
+    normalizedConfig = kernelDerivation.overrideAttrs({ ... }: {
       forceNormalizedConfig = false;
       buildPhase = "echo Skipping build phase...";
       installPhase = ''
@@ -284,7 +350,7 @@ let kernel = stdenv.mkDerivation {
       '';
     });
     # Patching over this configuration to expose menuconfig.
-    menuconfig = kernel.overrideAttrs({nativeBuildInputs ? [] , ...}: {
+    menuconfig = kernelDerivation.overrideAttrs({nativeBuildInputs ? [] , ...}: {
       nativeBuildInputs = nativeBuildInputs ++ [
         ncurses
         pkgconfig-helper
@@ -374,5 +440,6 @@ let kernel = stdenv.mkDerivation {
       '';
     });
   };
-};
-in kernel
+  # }}}
+});
+in kernelDerivation
diff --git a/overlay/mobile-nixos/kernel/compiler-gcc6.h b/overlay/mobile-nixos/kernel/compiler-gcc6.h
new file mode 100644
index 000000000..844706318
--- /dev/null
+++ b/overlay/mobile-nixos/kernel/compiler-gcc6.h
@@ -0,0 +1,69 @@
+// SOURCE:
+// https://github.com/NextThingCo/CHIP-u-boot/issues/10#issuecomment-287515505
+
+#ifndef __LINUX_COMPILER_H
+#error "Please don't include <linux/compiler-gcc6.h> directly, include <linux/compiler.h> instead."
+#endif
+
+#define __used				__attribute__((__used__))
+#define __must_check			__attribute__((warn_unused_result))
+#define __compiler_offsetof(a, b)	__builtin_offsetof(a, b)
+
+/* Mark functions as cold. gcc will assume any path leading to a call
+   to them will be unlikely.  This means a lot of manual unlikely()s
+   are unnecessary now for any paths leading to the usual suspects
+   like BUG(), printk(), panic() etc. [but let's keep them for now for
+   older compilers]
+
+   Early snapshots of gcc 4.3 don't support this and we can't detect this
+   in the preprocessor, but we can live with this because they're unreleased.
+   Maketime probing would be overkill here.
+
+   gcc also has a __attribute__((__hot__)) to move hot functions into
+   a special section, but I don't see any sense in this right now in
+   the kernel context */
+#define __cold			__attribute__((__cold__))
+
+#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
+
+#ifndef __CHECKER__
+# define __compiletime_warning(message) __attribute__((warning(message)))
+# define __compiletime_error(message) __attribute__((error(message)))
+#endif /* __CHECKER__ */
+
+/*
+ * Mark a position in code as unreachable.  This can be used to
+ * suppress control flow warnings after asm blocks that transfer
+ * control elsewhere.
+ *
+ * Early snapshots of gcc 4.5 don't support this and we can't detect
+ * this in the preprocessor, but we can live with this because they're
+ * unreleased.  Really, we need to have autoconf for the kernel.
+ */
+#define unreachable() __builtin_unreachable()
+
+/* Mark a function definition as prohibited from being cloned. */
+#define __noclone	__attribute__((__noclone__))
+
+/*
+ * Tell the optimizer that something else uses this function or variable.
+ */
+#define __visible __attribute__((externally_visible))
+
+/*
+ * GCC 'asm goto' miscompiles certain code sequences:
+ *
+ *   http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
+ *
+ * Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
+ *
+ * (asm goto is automatically volatile - the naming reflects this.)
+ */
+#define asm_volatile_goto(x...)	do { asm goto(x); asm (""); } while (0)
+
+#ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP
+#define __HAVE_BUILTIN_BSWAP32__
+#define __HAVE_BUILTIN_BSWAP64__
+#define __HAVE_BUILTIN_BSWAP16__
+#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */
+

From 1889893a4328725c90c9a66120fa4af6645c6644 Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Thu, 1 Oct 2020 18:56:08 -0400
Subject: [PATCH 02/32] kernel-builder: implement QCDT configuration in the
 builder

---
 modules/system-types/android/default.nix |  4 ++++
 overlay/mobile-nixos/kernel/builder.nix  | 24 ++++++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/modules/system-types/android/default.nix b/modules/system-types/android/default.nix
index fb8809aba..be350c30b 100644
--- a/modules/system-types/android/default.nix
+++ b/modules/system-types/android/default.nix
@@ -130,6 +130,10 @@ in
       };
     })
 
+    (lib.mkIf kernelPackage.isQcdt {
+      mobile.system.android.bootimg.dt = "${kernelPackage}/dt.img";
+    })
+
     {
       mobile.boot.stage-1.bootConfig = {
         device = {
diff --git a/overlay/mobile-nixos/kernel/builder.nix b/overlay/mobile-nixos/kernel/builder.nix
index ddc8d8a3e..71885159e 100644
--- a/overlay/mobile-nixos/kernel/builder.nix
+++ b/overlay/mobile-nixos/kernel/builder.nix
@@ -30,6 +30,7 @@
 , libmpc
 , mpfr
 , dtc
+, dtbTool
 
 , libelf
 , utillinux
@@ -65,6 +66,10 @@ in
 # Additionally, a config file is required.
 , configfile
 
+# Handling of QCDT dt.img
+, isQcdt ? false
+, qcdt_dtbs ? "arch/${platform.kernelArch}/boot/"
+
 # Togglable common quirks
 , enableCenteredLinuxLogo ? true
 , enableLinuxLogoReplacement ? true
@@ -127,6 +132,7 @@ let kernelDerivation =
 stdenv.mkDerivation (inputArgs // {
   pname = "linux";
   inherit src version file;
+  inherit qcdt_dtbs;
 
   # Allows disabling the kernel config normalization.
   # Set to false when normalizing the kernel config.
@@ -141,6 +147,7 @@ stdenv.mkDerivation (inputArgs // {
     # Mobile NixOS inputs.
     # While some kernels might not need those, most will.
     ++ [ dtc ] 
+    ++ optional isQcdt dtbTool
     ++ nativeBuildInputs
   ;
 
@@ -309,11 +316,24 @@ stdenv.mkDerivation (inputArgs // {
   ;
 
   postInstall = ''
+    echo ":: Copying configuration file"
     # Helpful in cases where the kernel isn't built with /proc/config.gz
     cp -v "$buildRoot/.config" "$out/build.config"
+
   '' + optionalString hasDTB ''
+    echo ":: Installing DTBs"
     mkdir -p $out/dtbs/
     make $makeFlags "''${makeFlagsArray[@]}" dtbs dtbs_install INSTALL_DTBS_PATH=$out/dtbs
+
+  '' + optionalString isQcdt ''
+    echo ":: Making and installing QCDT dt.img"
+    (PS4=" $ "; set -x
+    mkdir -p $out/
+    dtbTool -s 2048 -p "scripts/dtc/" \
+      -o "$out/dt.img" \
+      "$qcdt_dtbs"
+    )
+
   ''
     + maybeString postInstall
   ;
@@ -342,6 +362,10 @@ stdenv.mkDerivation (inputArgs // {
 
   # {{{
   passthru = {
+    # This is an "API" for the kernel derivation.
+    inherit isQcdt;
+
+    # Derivation with the as-built normalized kernel config
     normalizedConfig = kernelDerivation.overrideAttrs({ ... }: {
       forceNormalizedConfig = false;
       buildPhase = "echo Skipping build phase...";

From 9bac03b2f3a21aa7f6a9cd279563b630b75c9c92 Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Thu, 1 Oct 2020 23:19:47 -0400
Subject: [PATCH 03/32] kernel-builder: Encapsulate compressed images and dtb
 appended images

---
 overlay/mobile-nixos/kernel/builder.nix | 46 ++++++++++++++++++-------
 1 file changed, 33 insertions(+), 13 deletions(-)

diff --git a/overlay/mobile-nixos/kernel/builder.nix b/overlay/mobile-nixos/kernel/builder.nix
index 71885159e..d4c96c2d8 100644
--- a/overlay/mobile-nixos/kernel/builder.nix
+++ b/overlay/mobile-nixos/kernel/builder.nix
@@ -70,6 +70,11 @@ in
 , isQcdt ? false
 , qcdt_dtbs ? "arch/${platform.kernelArch}/boot/"
 
+# Enable support for android-specific "Image.gz-dtb" appended images
+, isImageGzDtb ? false
+# Mark the kernel as compressed, assumes .gz
+, isCompressed ? "gz"
+
 # Togglable common quirks
 , enableCenteredLinuxLogo ? true
 , enableLinuxLogoReplacement ? true
@@ -85,11 +90,7 @@ in
 , prePatch ? null
 , postPatch ? null
 , postInstall ? null
-
-# Part of the "API" of the kernel builder.
-# Image builders expect this attribute to know where to find the kernel file.
-# XXX : review if we can detect this instead in a safe manner
-, file ? stdenv.hostPlatform.platform.kernelTarget
+, installTargets ? []
 
 # Part of the usual NixOS kernel builder API
 , installsFirmware ? true
@@ -122,7 +123,11 @@ let
     exec ${buildPackages.pkgconfig}/bin/${buildPackages.pkgconfig.targetPrefix}pkg-config "$@"
   '';
 
-  hasDTB = stdenv.hostPlatform.platform.kernelDTB;
+  hasDTB = platform.kernelDTB;
+  kernelFileExtension = if isCompressed != false then ".${isCompressed}" else "";
+  kernelTarget = if platform.kernelTarget == "Image"
+    then "${platform.kernelTarget}${kernelFileExtension}"
+    else platform.kernelTarget;
 in
 
 # This `let` block allows us to have a self-reference to this derivation.
@@ -131,7 +136,7 @@ let kernelDerivation =
 
 stdenv.mkDerivation (inputArgs // {
   pname = "linux";
-  inherit src version file;
+  inherit src version;
   inherit qcdt_dtbs;
 
   # Allows disabling the kernel config normalization.
@@ -140,7 +145,7 @@ stdenv.mkDerivation (inputArgs // {
 
   depsBuildBuild = [ buildPackages.stdenv.cc ];
   nativeBuildInputs = [ perl bc nettools openssl rsync gmp libmpc mpfr ]
-    ++ optional (stdenv.hostPlatform.platform.kernelTarget == "uImage") buildPackages.ubootTools
+    ++ optional (platform.kernelTarget == "uImage") buildPackages.ubootTools
     ++ optional (stdenv.lib.versionAtLeast version "4.14") libelf
     ++ optional (stdenv.lib.versionAtLeast version "4.15") utillinux
     ++ optionals (stdenv.lib.versionAtLeast version "4.16") [ bison flex ]
@@ -301,9 +306,10 @@ stdenv.mkDerivation (inputArgs // {
 
   buildFlags = [
     "KBUILD_BUILD_VERSION=1-mobile-nixos"
-    platform.kernelTarget
+    kernelTarget
     "vmlinux"  # for "perf" and things like that
   ]
+    ++ optional isImageGzDtb "${kernelTarget}-dtb"
     ++ optional isModular "modules"
   ;
 
@@ -315,6 +321,13 @@ stdenv.mkDerivation (inputArgs // {
     ++ optional installsFirmware "INSTALL_FW_PATH=$(out)/lib/firmware"
   ;
 
+  installTargets = [
+    "install"
+  ]
+    ++ optional (isCompressed != false) "zinstall"
+    ++ installTargets
+  ;
+
   postInstall = ''
     echo ":: Copying configuration file"
     # Helpful in cases where the kernel isn't built with /proc/config.gz
@@ -334,6 +347,10 @@ stdenv.mkDerivation (inputArgs // {
       "$qcdt_dtbs"
     )
 
+  '' + optionalString isImageGzDtb ''
+    echo ":: Copying platform-specific -dtb image file"
+    cp -v "$buildRoot/arch/${platform.kernelArch}/boot/${kernelTarget}-dtb" "$out/"
+
   ''
     + maybeString postInstall
   ;
@@ -344,11 +361,11 @@ stdenv.mkDerivation (inputArgs // {
     "O=$(buildRoot)"
     "CC=${stdenv.cc}/bin/${stdenv.cc.targetPrefix}cc"
     "HOSTCC=${buildPackages.stdenv.cc}/bin/${buildPackages.stdenv.cc.targetPrefix}cc"
-    "ARCH=${stdenv.hostPlatform.platform.kernelArch}"
+    "ARCH=${platform.kernelArch}"
     "DTC_EXT=${buildPackages.dtc}/bin/dtc"
   ]
   # Use platform-specific flags
-  ++ stdenv.lib.optionals (stdenv.hostPlatform.platform ? kernelMakeFlags) stdenv.hostPlatform.platform.kernelMakeFlags
+  ++ stdenv.lib.optionals (platform ? kernelMakeFlags) platform.kernelMakeFlags
   # Mark as cross-compilation
   ++ stdenv.lib.optional (stdenv.hostPlatform != stdenv.buildPlatform) [ "CROSS_COMPILE=${stdenv.cc.targetPrefix}" ]
   # User-provided makeFlags
@@ -365,6 +382,9 @@ stdenv.mkDerivation (inputArgs // {
     # This is an "API" for the kernel derivation.
     inherit isQcdt;
 
+    # Internal API representing the filename of the desired output.
+    file = kernelTarget + optionalString isImageGzDtb "-dtb";
+
     # Derivation with the as-built normalized kernel config
     normalizedConfig = kernelDerivation.overrideAttrs({ ... }: {
       forceNormalizedConfig = false;
@@ -450,8 +470,8 @@ stdenv.mkDerivation (inputArgs // {
         export PATH="$PATH:${buildPackages.gnumake}/bin"
         export KCONFIG_CONFIG="\$(readlink -f "\$1")"; shift
 
-        export SRCARCH="${stdenv.hostPlatform.platform.kernelArch}"
-        export ARCH="${stdenv.hostPlatform.platform.kernelArch}"
+        export SRCARCH="${platform.kernelArch}"
+        export ARCH="${platform.kernelArch}"
         export KERNELVERSION="${version}"
         cd "\$KERNEL_TREE"
         ${/* We're expanding the builder's makeFlags variable here. This is not a mistake. */""}

From e8cd8a95cce5be48322a8a53b8f722e10a804138 Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Fri, 2 Oct 2020 18:18:57 -0400
Subject: [PATCH 04/32] kernel-builder: minor fixups

---
 overlay/mobile-nixos/kernel/builder.nix | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/overlay/mobile-nixos/kernel/builder.nix b/overlay/mobile-nixos/kernel/builder.nix
index d4c96c2d8..c568f9889 100644
--- a/overlay/mobile-nixos/kernel/builder.nix
+++ b/overlay/mobile-nixos/kernel/builder.nix
@@ -56,9 +56,9 @@ let
 in
 
 # This is the builder function signature.
-
+{
 # We have to be provided with a source
-{ src
+  src
 # And a version
 , version
 , modDirVersion ? modDirify version
@@ -72,14 +72,21 @@ in
 
 # Enable support for android-specific "Image.gz-dtb" appended images
 , isImageGzDtb ? false
+
 # Mark the kernel as compressed, assumes .gz
 , isCompressed ? "gz"
 
-# Togglable common quirks
+# Linux logo centering (as a boot logo)
 , enableCenteredLinuxLogo ? true
+
+# Linux logo replacement
 , enableLinuxLogoReplacement ? true
 , linuxLogo224PPMFile ? ./logo_linux_clut224.ppm
+
+# Mainly to mask issues with newer compilers
 , enableRemovingWerror ? false
+
+# Older kernels don't know about gcc6+, and this is needed
 , enableCompilerGcc6Quirk ? false
 
 # Usual stdenv arguments we are also setting.
@@ -340,12 +347,10 @@ stdenv.mkDerivation (inputArgs // {
 
   '' + optionalString isQcdt ''
     echo ":: Making and installing QCDT dt.img"
-    (PS4=" $ "; set -x
     mkdir -p $out/
     dtbTool -s 2048 -p "scripts/dtc/" \
       -o "$out/dt.img" \
       "$qcdt_dtbs"
-    )
 
   '' + optionalString isImageGzDtb ''
     echo ":: Copying platform-specific -dtb image file"
@@ -377,12 +382,12 @@ stdenv.mkDerivation (inputArgs // {
   enableParallelBuilding = true;
   dontStrip = true;
 
-  # {{{
   passthru = {
-    # This is an "API" for the kernel derivation.
+    # Used by consumers of the kernel derivation to configure the build
+    # appropriately for QCDT use.
     inherit isQcdt;
 
-    # Internal API representing the filename of the desired output.
+    # Used by consumers to refer to the kernel build product.
     file = kernelTarget + optionalString isImageGzDtb "-dtb";
 
     # Derivation with the as-built normalized kernel config
@@ -393,6 +398,7 @@ stdenv.mkDerivation (inputArgs // {
         cp .config $out
       '';
     });
+
     # Patching over this configuration to expose menuconfig.
     menuconfig = kernelDerivation.overrideAttrs({nativeBuildInputs ? [] , ...}: {
       nativeBuildInputs = nativeBuildInputs ++ [
@@ -484,6 +490,5 @@ stdenv.mkDerivation (inputArgs // {
       '';
     });
   };
-  # }}}
 });
 in kernelDerivation

From 47f6fc05b0ba403998cf7abcd80ef1130bb17c5e Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Thu, 1 Oct 2020 02:13:50 -0400
Subject: [PATCH 05/32] asus-dumo: Update usage of kernel builder

---
 devices/asus-dumo/kernel/default.nix | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/devices/asus-dumo/kernel/default.nix b/devices/asus-dumo/kernel/default.nix
index ca507b711..ec0b48a60 100644
--- a/devices/asus-dumo/kernel/default.nix
+++ b/devices/asus-dumo/kernel/default.nix
@@ -5,12 +5,10 @@
 , kernelPatches ? [] # FIXME
 }:
 
-(mobile-nixos.kernel-builder {
+mobile-nixos.kernel-builder {
   version = "5.8.0";
   configfile = ./config.aarch64;
 
-  hasDTB = true;
-
   src = fetchFromGitHub {
     owner = "torvalds";
     repo = "linux";
@@ -26,4 +24,4 @@
   ];
 
   isModular = false;
-})
+}

From 8f59c5b4417fb36f71127861f18e7a33ecf2eaaf Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Thu, 1 Oct 2020 02:16:14 -0400
Subject: [PATCH 06/32] asus-flo: Update usage of kernel builder

---
 devices/asus-flo/kernel/compiler-gcc6.h | 69 -------------------------
 devices/asus-flo/kernel/default.nix     | 32 ++----------
 2 files changed, 3 insertions(+), 98 deletions(-)
 delete mode 100644 devices/asus-flo/kernel/compiler-gcc6.h

diff --git a/devices/asus-flo/kernel/compiler-gcc6.h b/devices/asus-flo/kernel/compiler-gcc6.h
deleted file mode 100644
index 844706318..000000000
--- a/devices/asus-flo/kernel/compiler-gcc6.h
+++ /dev/null
@@ -1,69 +0,0 @@
-// SOURCE:
-// https://github.com/NextThingCo/CHIP-u-boot/issues/10#issuecomment-287515505
-
-#ifndef __LINUX_COMPILER_H
-#error "Please don't include <linux/compiler-gcc6.h> directly, include <linux/compiler.h> instead."
-#endif
-
-#define __used				__attribute__((__used__))
-#define __must_check			__attribute__((warn_unused_result))
-#define __compiler_offsetof(a, b)	__builtin_offsetof(a, b)
-
-/* Mark functions as cold. gcc will assume any path leading to a call
-   to them will be unlikely.  This means a lot of manual unlikely()s
-   are unnecessary now for any paths leading to the usual suspects
-   like BUG(), printk(), panic() etc. [but let's keep them for now for
-   older compilers]
-
-   Early snapshots of gcc 4.3 don't support this and we can't detect this
-   in the preprocessor, but we can live with this because they're unreleased.
-   Maketime probing would be overkill here.
-
-   gcc also has a __attribute__((__hot__)) to move hot functions into
-   a special section, but I don't see any sense in this right now in
-   the kernel context */
-#define __cold			__attribute__((__cold__))
-
-#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
-
-#ifndef __CHECKER__
-# define __compiletime_warning(message) __attribute__((warning(message)))
-# define __compiletime_error(message) __attribute__((error(message)))
-#endif /* __CHECKER__ */
-
-/*
- * Mark a position in code as unreachable.  This can be used to
- * suppress control flow warnings after asm blocks that transfer
- * control elsewhere.
- *
- * Early snapshots of gcc 4.5 don't support this and we can't detect
- * this in the preprocessor, but we can live with this because they're
- * unreleased.  Really, we need to have autoconf for the kernel.
- */
-#define unreachable() __builtin_unreachable()
-
-/* Mark a function definition as prohibited from being cloned. */
-#define __noclone	__attribute__((__noclone__))
-
-/*
- * Tell the optimizer that something else uses this function or variable.
- */
-#define __visible __attribute__((externally_visible))
-
-/*
- * GCC 'asm goto' miscompiles certain code sequences:
- *
- *   http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
- *
- * Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
- *
- * (asm goto is automatically volatile - the naming reflects this.)
- */
-#define asm_volatile_goto(x...)	do { asm goto(x); asm (""); } while (0)
-
-#ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP
-#define __HAVE_BUILTIN_BSWAP32__
-#define __HAVE_BUILTIN_BSWAP64__
-#define __HAVE_BUILTIN_BSWAP16__
-#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */
-
diff --git a/devices/asus-flo/kernel/default.nix b/devices/asus-flo/kernel/default.nix
index e9697f8f6..43d86805e 100644
--- a/devices/asus-flo/kernel/default.nix
+++ b/devices/asus-flo/kernel/default.nix
@@ -4,12 +4,10 @@
 , kernelPatches ? [] # FIXME
 }:
 
-(mobile-nixos.kernel-builder-gcc6 {
+mobile-nixos.kernel-builder-gcc6 {
   version = "3.4.113";
   configfile = ./config.armv7;
 
-  file = "zImage";
-
   src = fetchFromGitHub {
     owner = "LineageOS";
     repo = "android_kernel_google_msm";
@@ -27,30 +25,6 @@
     ./99_framebuffer.patch
   ];
 
+  enableCompilerGcc6Quirk = true;
   isModular = false;
-
-  postPatch = ''
-    cp -v "${./compiler-gcc6.h}" "./include/linux/compiler-gcc6.h"
-  '';
-}).overrideAttrs({ postInstall ? "", ... }: {
-  installTargets = [ "zinstall" ];
-  postInstall = postInstall + ''
-    mkdir -p "$out/boot"
-
-    # FIXME factor this out properly
-    # Copies all potential output files.
-    for f in zImage-dtb Image.gz-dtb zImage Image.gz Image; do
-      f=arch/arm/boot/$f
-      [ -e "$f" ] || continue
-      echo "zImage found: $f"
-      cp -v "$f" "$out/"
-      break
-    done
-
-    mkdir -p $out/dtb
-    for f in arch/*/boot/dts/*.dtb; do
-      cp -v "$f" $out/dtb/
-    done
-
-  '';
-})
+}

From c15684ddca7d8af4f6721a3649894227d65f6a45 Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Thu, 1 Oct 2020 02:16:20 -0400
Subject: [PATCH 07/32] asus-x018d: Update usage of kernel builder

---
 devices/asus-x018d/kernel/default.nix | 28 +++++----------------------
 1 file changed, 5 insertions(+), 23 deletions(-)

diff --git a/devices/asus-x018d/kernel/default.nix b/devices/asus-x018d/kernel/default.nix
index afbd1bd2a..a510c9a14 100644
--- a/devices/asus-x018d/kernel/default.nix
+++ b/devices/asus-x018d/kernel/default.nix
@@ -6,16 +6,10 @@
 , buildPackages
 }:
 
-let
-  inherit (buildPackages) dtc;
-in
-(mobile-nixos.kernel-builder-gcc49 {
+mobile-nixos.kernel-builder-gcc49 {
   version = "3.18.35";
   configfile = ./config.aarch64;
 
-  file = "Image.gz-dtb";
-  hasDTB = true;
-
   src = fetchFromGitHub {
     owner = "mobile-nixos";
     repo = "linux";
@@ -32,23 +26,11 @@ in
     ./0002-E262L-Green-LED-now-defaults-to-on.patch
   ];
 
-  makeFlags = [
-    "DTC_EXT=${dtc}/bin/dtc"
-  ];
-
-  isModular = false;
-
-  postPatch = ''
-    patchShebangs tools
-  '';
-
   nativeBuildInputs = [
+    # Needed for tools/dct/DrvGen.py
     python2
   ];
-}).overrideAttrs({ postInstall ? "", ... }: {
-  installTargets = [ "zinstall" "Image.gz-dtb" "install" ];
 
-  postInstall = postInstall + ''
-    cp -v "$buildRoot/arch/arm64/boot/Image.gz-dtb" "$out/"
-  '';
-})
+  isImageGzDtb = true;
+  isModular = false;
+}

From 7dc514e8ce930f5d4c8936a5c0a25da2240d9a3d Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Thu, 1 Oct 2020 02:16:27 -0400
Subject: [PATCH 08/32] asus-z00t: Update usage of kernel builder

---
 devices/asus-z00t/default.nix            |  1 -
 devices/asus-z00t/kernel/compiler-gcc6.h | 69 ------------------------
 devices/asus-z00t/kernel/default.nix     | 32 ++---------
 3 files changed, 4 insertions(+), 98 deletions(-)
 delete mode 100644 devices/asus-z00t/kernel/compiler-gcc6.h

diff --git a/devices/asus-z00t/default.nix b/devices/asus-z00t/default.nix
index 3f2007562..c2a8d3cf7 100644
--- a/devices/asus-z00t/default.nix
+++ b/devices/asus-z00t/default.nix
@@ -25,7 +25,6 @@
   mobile.device.firmware = pkgs.callPackage ./firmware {};
 
   mobile.system.android.bootimg = {
-    dt = "${config.mobile.boot.stage-1.kernel.package}/dtbs/asus-z00t.img";
     flash = {
       offset_base = "0x10000000";
       offset_kernel = "0x00008000";
diff --git a/devices/asus-z00t/kernel/compiler-gcc6.h b/devices/asus-z00t/kernel/compiler-gcc6.h
deleted file mode 100644
index 844706318..000000000
--- a/devices/asus-z00t/kernel/compiler-gcc6.h
+++ /dev/null
@@ -1,69 +0,0 @@
-// SOURCE:
-// https://github.com/NextThingCo/CHIP-u-boot/issues/10#issuecomment-287515505
-
-#ifndef __LINUX_COMPILER_H
-#error "Please don't include <linux/compiler-gcc6.h> directly, include <linux/compiler.h> instead."
-#endif
-
-#define __used				__attribute__((__used__))
-#define __must_check			__attribute__((warn_unused_result))
-#define __compiler_offsetof(a, b)	__builtin_offsetof(a, b)
-
-/* Mark functions as cold. gcc will assume any path leading to a call
-   to them will be unlikely.  This means a lot of manual unlikely()s
-   are unnecessary now for any paths leading to the usual suspects
-   like BUG(), printk(), panic() etc. [but let's keep them for now for
-   older compilers]
-
-   Early snapshots of gcc 4.3 don't support this and we can't detect this
-   in the preprocessor, but we can live with this because they're unreleased.
-   Maketime probing would be overkill here.
-
-   gcc also has a __attribute__((__hot__)) to move hot functions into
-   a special section, but I don't see any sense in this right now in
-   the kernel context */
-#define __cold			__attribute__((__cold__))
-
-#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
-
-#ifndef __CHECKER__
-# define __compiletime_warning(message) __attribute__((warning(message)))
-# define __compiletime_error(message) __attribute__((error(message)))
-#endif /* __CHECKER__ */
-
-/*
- * Mark a position in code as unreachable.  This can be used to
- * suppress control flow warnings after asm blocks that transfer
- * control elsewhere.
- *
- * Early snapshots of gcc 4.5 don't support this and we can't detect
- * this in the preprocessor, but we can live with this because they're
- * unreleased.  Really, we need to have autoconf for the kernel.
- */
-#define unreachable() __builtin_unreachable()
-
-/* Mark a function definition as prohibited from being cloned. */
-#define __noclone	__attribute__((__noclone__))
-
-/*
- * Tell the optimizer that something else uses this function or variable.
- */
-#define __visible __attribute__((externally_visible))
-
-/*
- * GCC 'asm goto' miscompiles certain code sequences:
- *
- *   http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
- *
- * Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
- *
- * (asm goto is automatically volatile - the naming reflects this.)
- */
-#define asm_volatile_goto(x...)	do { asm goto(x); asm (""); } while (0)
-
-#ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP
-#define __HAVE_BUILTIN_BSWAP32__
-#define __HAVE_BUILTIN_BSWAP64__
-#define __HAVE_BUILTIN_BSWAP16__
-#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */
-
diff --git a/devices/asus-z00t/kernel/default.nix b/devices/asus-z00t/kernel/default.nix
index cf608f087..465731d79 100644
--- a/devices/asus-z00t/kernel/default.nix
+++ b/devices/asus-z00t/kernel/default.nix
@@ -2,16 +2,12 @@
   mobile-nixos
 , fetchFromGitHub
 , kernelPatches ? [] # FIXME
-, dtbTool
 }:
 
-(mobile-nixos.kernel-builder-gcc6 {
+mobile-nixos.kernel-builder-gcc6 {
   version = "3.10.108";
   configfile = ./config.aarch64;
 
-  file = "Image.gz";
-  hasDTB = true;
-
   src = fetchFromGitHub {
     owner = "LineageOS";
     repo = "android_kernel_asus_msm8916";
@@ -40,27 +36,7 @@
     ./90_dtbs-install.patch
     ./99_framebuffer.patch
   ];
-
+  qcdt_dtbs = "arch/arm/boot/";
   isModular = false;
-
-  postPatch = ''
-    cp -v "${./compiler-gcc6.h}" "./include/linux/compiler-gcc6.h"
-  '';
-}).overrideAttrs({ postInstall ? "", ... }: {
-  installTargets = [ "zinstall" ];
-  postInstall = postInstall + ''
-    ${dtbTool}/bin/dtbTool -s 2048 -p "scripts/dtc/" -o "arch/arm64/boot/asus-z00t.img" "arch/arm/boot/"
-    cp "arch/arm64/boot/asus-z00t.img" "$out/dtbs/asus-z00t.img"
-
-    mkdir -p $out/dtb
-    for f in arch/*/boot/dts/*.dtb; do
-      cp -v "$f" $out/dtb/
-    done
-
-#    # FIXME: understand the specifics of why this needs to be catted together.
-#    (
-#    cd $out
-#    cat Image.gz dtb/*.dtb > vmlinuz-dtb
-#    )
-  '';
-})
+  isQcdt = true;
+}

From f01f499a023e49b6288fac713bafd36d56deb4d6 Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Thu, 1 Oct 2020 02:16:43 -0400
Subject: [PATCH 09/32] google-marlin: Update usage of kernel builder

---
 devices/google-marlin/kernel/default.nix | 40 +++---------------------
 1 file changed, 4 insertions(+), 36 deletions(-)

diff --git a/devices/google-marlin/kernel/default.nix b/devices/google-marlin/kernel/default.nix
index f6142c496..1e54c52e0 100644
--- a/devices/google-marlin/kernel/default.nix
+++ b/devices/google-marlin/kernel/default.nix
@@ -2,19 +2,11 @@
   mobile-nixos
 , fetchFromGitHub
 , kernelPatches ? [] # FIXME
-, buildPackages
 }:
 
-let
-  inherit (buildPackages) dtc;
-in
-
-(mobile-nixos.kernel-builder-gcc6 {
+mobile-nixos.kernel-builder-gcc6 {
   configfile = ./config.aarch64;
 
-  file = "Image.gz-dtb";
-  hasDTB = true;
-
   version = "3.18.140";
   src = fetchFromGitHub {
     owner = "android-linux-stable";
@@ -29,31 +21,7 @@ in
     ./99_framebuffer.patch
   ];
 
+  enableRemovingWerror = true;
+  isImageGzDtb = true;
   isModular = false;
-
-  postPatch = ''
-    # FIXME : factor out
-    (
-    # Remove -Werror from all makefiles
-    local i
-    local makefiles="$(find . -type f -name Makefile)
-    $(find . -type f -name Kbuild)"
-    for i in $makefiles; do
-      sed -i 's/-Werror-/-W/g' "$i"
-      sed -i 's/-Werror=/-W/g' "$i"
-      sed -i 's/-Werror//g' "$i"
-    done
-    )
-
-    # Remove google's default dm-verity certs
-    rm -f *.x509
-  '';
-}).overrideAttrs({ postInstall ? "", nativeBuildInputs, ... }: {
-  installTargets = [ "zinstall" "Image.gz-dtb" "install" ];
-
-  nativeBuildInputs = nativeBuildInputs ++ [ dtc ];
-
-  postInstall = postInstall + ''
-    cp -v "$buildRoot/arch/arm64/boot/Image.gz-dtb" "$out/"
-  '';
-})
+}

From 802c0fbb50c1ab0d03860dda6cd7ded50c45aadf Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Thu, 1 Oct 2020 02:16:48 -0400
Subject: [PATCH 10/32] google-walleye: Update usage of kernel builder

---
 devices/google-walleye/kernel/default.nix | 37 +++--------------------
 1 file changed, 4 insertions(+), 33 deletions(-)

diff --git a/devices/google-walleye/kernel/default.nix b/devices/google-walleye/kernel/default.nix
index 5a719af4f..a8cc40c63 100644
--- a/devices/google-walleye/kernel/default.nix
+++ b/devices/google-walleye/kernel/default.nix
@@ -2,19 +2,11 @@
   mobile-nixos
 , fetchFromGitHub
 , kernelPatches ? [] # FIXME
-, buildPackages
 }:
 
-let
-  inherit (buildPackages) dtc;
-in
-
-(mobile-nixos.kernel-builder {
+mobile-nixos.kernel-builder {
   configfile = ./config.aarch64;
 
-  file = "Image.gz-dtb";
-  hasDTB = true;
-
   version = "4.4.230";
   src = fetchFromGitHub {
     owner = "android-linux-stable";
@@ -30,28 +22,7 @@ in
     ./0003-arch-arm64-Add-config-option-to-fix-bootloader-cmdli.patch
   ];
 
+  enableRemovingWerror = true;
+  isImageGzDtb = true;
   isModular = false;
-
-  postPatch = ''
-    # FIXME : factor out
-    (
-    # Remove -Werror from all makefiles
-    local i
-    local makefiles="$(find . -type f -name Makefile)
-    $(find . -type f -name Kbuild)"
-    for i in $makefiles; do
-      sed -i 's/-Werror-/-W/g' "$i"
-      sed -i 's/-Werror=/-W/g' "$i"
-      sed -i 's/-Werror//g' "$i"
-    done
-    )
-  '';
-}).overrideAttrs({ postInstall ? "", nativeBuildInputs, ... }: {
-  installTargets = [ "zinstall" "Image.gz-dtb" "install" ];
-
-  nativeBuildInputs = nativeBuildInputs ++ [ dtc ];
-
-  postInstall = postInstall + ''
-    cp -v "$buildRoot/arch/arm64/boot/Image.gz-dtb" "$out/"
-  '';
-})
+}

From ccd3a542fc967c357ad543ba8a6cac11880c2fc4 Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Thu, 1 Oct 2020 02:16:57 -0400
Subject: [PATCH 11/32] motorola-addison: Update usage of kernel builder

---
 devices/motorola-addison/default.nix          |  1 -
 .../motorola-addison/kernel/compiler-gcc6.h   | 69 -------------------
 devices/motorola-addison/kernel/default.nix   | 46 ++-----------
 3 files changed, 5 insertions(+), 111 deletions(-)
 delete mode 100644 devices/motorola-addison/kernel/compiler-gcc6.h

diff --git a/devices/motorola-addison/default.nix b/devices/motorola-addison/default.nix
index 5c73ff5dd..f7ebca2dc 100644
--- a/devices/motorola-addison/default.nix
+++ b/devices/motorola-addison/default.nix
@@ -22,7 +22,6 @@
   mobile.device.firmware = pkgs.callPackage ./firmware {};
 
   mobile.system.android.bootimg = {
-    dt = "${config.mobile.boot.stage-1.kernel.package}/dtbs/motorola-addison.img";
     flash = {
       offset_base = "0x80000000";
       offset_kernel = "0x00008000";
diff --git a/devices/motorola-addison/kernel/compiler-gcc6.h b/devices/motorola-addison/kernel/compiler-gcc6.h
deleted file mode 100644
index 844706318..000000000
--- a/devices/motorola-addison/kernel/compiler-gcc6.h
+++ /dev/null
@@ -1,69 +0,0 @@
-// SOURCE:
-// https://github.com/NextThingCo/CHIP-u-boot/issues/10#issuecomment-287515505
-
-#ifndef __LINUX_COMPILER_H
-#error "Please don't include <linux/compiler-gcc6.h> directly, include <linux/compiler.h> instead."
-#endif
-
-#define __used				__attribute__((__used__))
-#define __must_check			__attribute__((warn_unused_result))
-#define __compiler_offsetof(a, b)	__builtin_offsetof(a, b)
-
-/* Mark functions as cold. gcc will assume any path leading to a call
-   to them will be unlikely.  This means a lot of manual unlikely()s
-   are unnecessary now for any paths leading to the usual suspects
-   like BUG(), printk(), panic() etc. [but let's keep them for now for
-   older compilers]
-
-   Early snapshots of gcc 4.3 don't support this and we can't detect this
-   in the preprocessor, but we can live with this because they're unreleased.
-   Maketime probing would be overkill here.
-
-   gcc also has a __attribute__((__hot__)) to move hot functions into
-   a special section, but I don't see any sense in this right now in
-   the kernel context */
-#define __cold			__attribute__((__cold__))
-
-#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
-
-#ifndef __CHECKER__
-# define __compiletime_warning(message) __attribute__((warning(message)))
-# define __compiletime_error(message) __attribute__((error(message)))
-#endif /* __CHECKER__ */
-
-/*
- * Mark a position in code as unreachable.  This can be used to
- * suppress control flow warnings after asm blocks that transfer
- * control elsewhere.
- *
- * Early snapshots of gcc 4.5 don't support this and we can't detect
- * this in the preprocessor, but we can live with this because they're
- * unreleased.  Really, we need to have autoconf for the kernel.
- */
-#define unreachable() __builtin_unreachable()
-
-/* Mark a function definition as prohibited from being cloned. */
-#define __noclone	__attribute__((__noclone__))
-
-/*
- * Tell the optimizer that something else uses this function or variable.
- */
-#define __visible __attribute__((externally_visible))
-
-/*
- * GCC 'asm goto' miscompiles certain code sequences:
- *
- *   http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
- *
- * Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
- *
- * (asm goto is automatically volatile - the naming reflects this.)
- */
-#define asm_volatile_goto(x...)	do { asm goto(x); asm (""); } while (0)
-
-#ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP
-#define __HAVE_BUILTIN_BSWAP32__
-#define __HAVE_BUILTIN_BSWAP64__
-#define __HAVE_BUILTIN_BSWAP16__
-#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */
-
diff --git a/devices/motorola-addison/kernel/default.nix b/devices/motorola-addison/kernel/default.nix
index f8d4eb89e..14356ed6d 100644
--- a/devices/motorola-addison/kernel/default.nix
+++ b/devices/motorola-addison/kernel/default.nix
@@ -1,10 +1,8 @@
 {
   mobile-nixos
 , stdenv
-, hostPlatform
 , fetchFromGitHub
 , kernelPatches ? [] # FIXME
-, dtbTool
 }:
 
 #
@@ -16,16 +14,9 @@
 #  mobile.system.system = lib.mkForce "armv7l-linux";
 #
 
-let
-  inherit (stdenv.lib) optionalString;
-  cpuName = hostPlatform.parsed.cpu.name;
-in
-(mobile-nixos.kernel-builder-gcc6 {
+mobile-nixos.kernel-builder-gcc6 {
   version = "3.18.71";
-  configfile = ./. + "/config.${cpuName}";
-
-  file = if (cpuName == "aarch64") then "Image.gz" else "zImage";
-  hasDTB = (cpuName == "aarch64");
+  configfile = ./. + "/config.${stdenv.hostPlatform.parsed.cpu.name}";
 
   src = fetchFromGitHub {
     owner = "LineageOS";
@@ -43,34 +34,7 @@ in
     ./0005-Allow-building-with-sound-disabled.patch
   ];
 
+  enableRemovingWerror = true;
   isModular = false;
-
-  postPatch = ''
-    cp -v "${./compiler-gcc6.h}" "./include/linux/compiler-gcc6.h"
-
-    # FIXME : factor out
-    (
-    # Remove -Werror from all makefiles
-    local i
-    local makefiles="$(find . -type f -name Makefile)
-    $(find . -type f -name Kbuild)"
-    for i in $makefiles; do
-      sed -i 's/-Werror-/-W/g' "$i"
-      sed -i 's/-Werror=/-W/g' "$i"
-      sed -i 's/-Werror//g' "$i"
-    done
-    )
-  '';
-}).overrideAttrs({ postInstall ? "", ... }: {
-  installTargets = [ "zinstall" "dtbs" ];
-  postInstall = postInstall + ''
-    mkdir -p "$out/dtbs/"
-  ''
-  + optionalString (cpuName == "aarch64") ''
-    ${dtbTool}/bin/dtbTool -s 2048 -p "scripts/dtc/" -o "$out/dtbs/motorola-addison.img" "$out/dtbs/qcom/"
-  ''
-  + optionalString (cpuName == "armv7l") ''
-     ${dtbTool}/bin/dtbTool -s 2048 -p "scripts/dtc/" -o "$out/dtbs/motorola-addison.img" "arch/arm/boot"
-  ''
-  ;
-})
+  isQcdt = true;
+}

From 3c07e7f687584b961825d4fb19b3d2bd89126452 Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Thu, 1 Oct 2020 02:17:02 -0400
Subject: [PATCH 12/32] oneplus-oneplus3: Update usage of kernel builder

---
 .../oneplus-oneplus3/kernel/compiler-gcc6.h   | 69 -------------------
 devices/oneplus-oneplus3/kernel/default.nix   | 33 +--------
 2 files changed, 3 insertions(+), 99 deletions(-)
 delete mode 100644 devices/oneplus-oneplus3/kernel/compiler-gcc6.h

diff --git a/devices/oneplus-oneplus3/kernel/compiler-gcc6.h b/devices/oneplus-oneplus3/kernel/compiler-gcc6.h
deleted file mode 100644
index 844706318..000000000
--- a/devices/oneplus-oneplus3/kernel/compiler-gcc6.h
+++ /dev/null
@@ -1,69 +0,0 @@
-// SOURCE:
-// https://github.com/NextThingCo/CHIP-u-boot/issues/10#issuecomment-287515505
-
-#ifndef __LINUX_COMPILER_H
-#error "Please don't include <linux/compiler-gcc6.h> directly, include <linux/compiler.h> instead."
-#endif
-
-#define __used				__attribute__((__used__))
-#define __must_check			__attribute__((warn_unused_result))
-#define __compiler_offsetof(a, b)	__builtin_offsetof(a, b)
-
-/* Mark functions as cold. gcc will assume any path leading to a call
-   to them will be unlikely.  This means a lot of manual unlikely()s
-   are unnecessary now for any paths leading to the usual suspects
-   like BUG(), printk(), panic() etc. [but let's keep them for now for
-   older compilers]
-
-   Early snapshots of gcc 4.3 don't support this and we can't detect this
-   in the preprocessor, but we can live with this because they're unreleased.
-   Maketime probing would be overkill here.
-
-   gcc also has a __attribute__((__hot__)) to move hot functions into
-   a special section, but I don't see any sense in this right now in
-   the kernel context */
-#define __cold			__attribute__((__cold__))
-
-#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
-
-#ifndef __CHECKER__
-# define __compiletime_warning(message) __attribute__((warning(message)))
-# define __compiletime_error(message) __attribute__((error(message)))
-#endif /* __CHECKER__ */
-
-/*
- * Mark a position in code as unreachable.  This can be used to
- * suppress control flow warnings after asm blocks that transfer
- * control elsewhere.
- *
- * Early snapshots of gcc 4.5 don't support this and we can't detect
- * this in the preprocessor, but we can live with this because they're
- * unreleased.  Really, we need to have autoconf for the kernel.
- */
-#define unreachable() __builtin_unreachable()
-
-/* Mark a function definition as prohibited from being cloned. */
-#define __noclone	__attribute__((__noclone__))
-
-/*
- * Tell the optimizer that something else uses this function or variable.
- */
-#define __visible __attribute__((externally_visible))
-
-/*
- * GCC 'asm goto' miscompiles certain code sequences:
- *
- *   http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
- *
- * Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
- *
- * (asm goto is automatically volatile - the naming reflects this.)
- */
-#define asm_volatile_goto(x...)	do { asm goto(x); asm (""); } while (0)
-
-#ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP
-#define __HAVE_BUILTIN_BSWAP32__
-#define __HAVE_BUILTIN_BSWAP64__
-#define __HAVE_BUILTIN_BSWAP16__
-#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */
-
diff --git a/devices/oneplus-oneplus3/kernel/default.nix b/devices/oneplus-oneplus3/kernel/default.nix
index 20c7cb50b..15db75897 100644
--- a/devices/oneplus-oneplus3/kernel/default.nix
+++ b/devices/oneplus-oneplus3/kernel/default.nix
@@ -2,16 +2,11 @@
   mobile-nixos
 , fetchFromGitHub
 , kernelPatches ? [] # FIXME
-, buildPackages
-, dtbTool
 }:
 
-(mobile-nixos.kernel-builder-gcc6 {
+mobile-nixos.kernel-builder-gcc6 {
   configfile = ./config.aarch64;
 
-  file = "Image.gz-dtb";
-  hasDTB = true;
-
   version = "3.18.140";
   src = fetchFromGitHub {
     owner = "android-linux-stable";
@@ -27,28 +22,6 @@
     ./0001-oneplus3-Configure-LEDs-using-kernel-triggers.patch
   ];
 
+  isImageGzDtb = true;
   isModular = false;
-
-  postPatch = ''
-    cp -v "${./compiler-gcc6.h}" "./include/linux/compiler-gcc6.h"
-
-    # FIXME : factor out
-    (
-    # Remove -Werror from all makefiles
-    local i
-    local makefiles="$(find . -type f -name Makefile)
-    $(find . -type f -name Kbuild)"
-    for i in $makefiles; do
-      sed -i 's/-Werror-/-W/g' "$i"
-      sed -i 's/-Werror=/-W/g' "$i"
-      sed -i 's/-Werror//g' "$i"
-    done
-    )
-  '';
-}).overrideAttrs({ postInstall ? "", ... }: {
-  installTargets = [ "zinstall" "Image.gz-dtb" "install" ];
-  postInstall = postInstall + ''
-    mkdir -p "$out/dtbs/"
-    cp -v "$buildRoot/arch/arm64/boot/Image.gz-dtb" "$out/"
-  '';
-})
+}

From 52f48851bf709755216a3060a56105eea9d8f0c5 Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Thu, 1 Oct 2020 02:17:09 -0400
Subject: [PATCH 13/32] pine64-pinephone-braveheart: Update usage of kernel
 builder

---
 .../pine64-pinephone-braveheart/kernel/default.nix   | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/devices/pine64-pinephone-braveheart/kernel/default.nix b/devices/pine64-pinephone-braveheart/kernel/default.nix
index 9bbb116ba..e85079f7c 100644
--- a/devices/pine64-pinephone-braveheart/kernel/default.nix
+++ b/devices/pine64-pinephone-braveheart/kernel/default.nix
@@ -1,11 +1,10 @@
 {
   mobile-nixos
 , fetchFromGitHub
-, fetchpatch
 , kernelPatches ? [] # FIXME
 }:
 
-(mobile-nixos.kernel-builder {
+mobile-nixos.kernel-builder {
   version = "5.8.0";
   configfile = ./config.aarch64;
   src = fetchFromGitHub {
@@ -17,10 +16,11 @@
   patches = [
     ./0001-dts-pinephone-Setup-default-on-and-panic-LEDs.patch
   ];
-}).overrideAttrs({ postInstall ? "", ... }: {
-  installTargets = [ "install" "dtbs" ];
-  postInstall = postInstall + ''
+
+  # Install *only* the desired FDTs
+  postInstall = ''
+    echo ":: Installing FDTs"
     mkdir -p "$out/dtbs/allwinner"
     cp -v $buildRoot/arch/arm64/boot/dts/allwinner/sun50i-a64-pinephone-*.dtb $out/dtbs/allwinner/
   '';
-})
+}

From b4e30da9e5d20c2021240cdc57af22ddbaf589d0 Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Thu, 1 Oct 2020 02:17:20 -0400
Subject: [PATCH 14/32] sony-pioneer: Update usage of kernel builder

---
 devices/sony-pioneer/kernel/default.nix | 22 +++-------------------
 1 file changed, 3 insertions(+), 19 deletions(-)

diff --git a/devices/sony-pioneer/kernel/default.nix b/devices/sony-pioneer/kernel/default.nix
index f7b51b954..2754ad5de 100644
--- a/devices/sony-pioneer/kernel/default.nix
+++ b/devices/sony-pioneer/kernel/default.nix
@@ -2,19 +2,12 @@
   mobile-nixos
 , fetchFromGitHub
 , kernelPatches ? [] # FIXME
-, buildPackages
 }:
 
-let
-  inherit (buildPackages) dtc;
-in
-(mobile-nixos.kernel-builder-gcc49 {
+mobile-nixos.kernel-builder-gcc49 {
   version = "4.4.205";
   configfile = ./config.aarch64;
 
-  file = "Image.gz-dtb";
-  hasDTB = true;
-
   # https://github.com/LineageOS/android_kernel_sony_sdm660
   src = fetchFromGitHub {
     owner = "LineageOS";
@@ -30,15 +23,6 @@ in
     ./0003-arch-arm64-Add-config-option-to-fix-bootloader-cmdli.patch
   ];
 
-  makeFlags = [
-    "DTC_EXT=${dtc}/bin/dtc"
-  ];
-
+  isImageGzDtb = true;
   isModular = false;
-
-}).overrideAttrs({ postInstall ? "", ... }: {
-  installTargets = [ "zinstall" "Image.gz-dtb" "install" ];
-  postInstall = postInstall + ''
-    cp -v "$buildRoot/arch/arm64/boot/Image.gz-dtb" "$out/"
-  '';
-})
+}

From 0b9b59776c5be27349198314b2160305905c4541 Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Thu, 1 Oct 2020 02:17:25 -0400
Subject: [PATCH 15/32] xiaomi-begonia: Update usage of kernel builder

---
 devices/xiaomi-begonia/kernel/default.nix | 29 ++++-------------------
 1 file changed, 4 insertions(+), 25 deletions(-)

diff --git a/devices/xiaomi-begonia/kernel/default.nix b/devices/xiaomi-begonia/kernel/default.nix
index 3594783d6..47755e11d 100644
--- a/devices/xiaomi-begonia/kernel/default.nix
+++ b/devices/xiaomi-begonia/kernel/default.nix
@@ -1,6 +1,5 @@
 {
   mobile-nixos
-, runCommand
 , fetchFromGitHub
 , kernelPatches ? [] # FIXME
 , buildPackages
@@ -28,8 +27,6 @@ let
     sha256 = "1p08392pcavfjy5i0zc61dxibr0jq9kb3na1hdx85q0z3d9sfwp6";
   };
 
-  inherit (buildPackages) dtc;
-
   # This may seem weird, but doing this inside the kernel build breaks the binary.
   # Note that `buildPackages.stdenv` is necessary since this is a tool for the host.
   dtc_overlay = buildPackages.stdenv.mkDerivation {
@@ -54,13 +51,11 @@ let
   };
 
 in
-(mobile-nixos.kernel-builder-clang_9 {
+  
+mobile-nixos.kernel-builder-clang_9 {
   version = "4.14.184";
   configfile = ./config.aarch64;
 
-  file = "Image.gz-dtb";
-  hasDTB = true;
-
   inherit src;
 
   patches = [
@@ -71,10 +66,7 @@ in
     ./0003-arch-arm64-Add-config-option-to-fix-bootloader-cmdli.patch
   ];
 
-  makeFlags = [
-    "DTC_EXT=${dtc}/bin/dtc"
-  ];
-
+  isImageGzDtb = true;
   isModular = false;
 
   postPatch = ''
@@ -84,17 +76,4 @@ in
     cp ${dtc_overlay} scripts/dtc/dtc_overlay
     )
   '';
-}).overrideAttrs({ postInstall ? "", ... }: {
-  installTargets = [
-    # uh, things seem screwey with that vendor kernel tree, and dependencies
-    # are not resolved as expected, so let's ask for the compressed kernel
-    # explictly first :/.
-    "Image.gz"
-    "zinstall"
-    "Image.gz-dtb"
-    "install"
-  ];
-  postInstall = postInstall + ''
-    cp -v "$buildRoot/arch/arm64/boot/Image.gz-dtb" "$out/"
-  '';
-})
+}

From 9356bbd9aa0496f1d773cf7f8d5729ca0279621a Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Thu, 1 Oct 2020 02:17:31 -0400
Subject: [PATCH 16/32] xiaomi-lavender: Update usage of kernel builder

---
 devices/xiaomi-lavender/kernel/default.nix | 23 +++-------------------
 1 file changed, 3 insertions(+), 20 deletions(-)

diff --git a/devices/xiaomi-lavender/kernel/default.nix b/devices/xiaomi-lavender/kernel/default.nix
index 2d4bc06a4..b1836082d 100644
--- a/devices/xiaomi-lavender/kernel/default.nix
+++ b/devices/xiaomi-lavender/kernel/default.nix
@@ -2,7 +2,6 @@
   mobile-nixos
 , fetchFromGitHub
 , kernelPatches ? [] # FIXME
-, buildPackages
 }:
 
 #
@@ -12,20 +11,13 @@
 #
 # Things to note:
 #
-#  * The build will not succeed using the `dtc` scripts shipped with their kernel.
 #  * Will not build or boot on all compilers.
 #
 
-let
-  inherit (buildPackages) dtc;
-in
-(mobile-nixos.kernel-builder-gcc49 {
+mobile-nixos.kernel-builder-gcc49 {
   version = "4.4.153";
   configfile = ./config.aarch64;
 
-  file = "Image.gz-dtb";
-  hasDTB = true;
-
   # https://github.com/MiCode/Xiaomi_Kernel_OpenSource/tree/lavender-p-oss
   src = fetchFromGitHub {
     owner = "MiCode";
@@ -40,15 +32,6 @@ in
     ./0003-arch-arm64-Add-config-option-to-fix-bootloader-cmdli.patch
   ];
 
-  makeFlags = [
-    "DTC_EXT=${dtc}/bin/dtc"
-  ];
-
+  isImageGzDtb = true;
   isModular = false;
-
-}).overrideAttrs({ postInstall ? "", ... }: {
-  installTargets = [ "zinstall" "Image.gz-dtb" "install" ];
-  postInstall = postInstall + ''
-    cp -v "$buildRoot/arch/arm64/boot/Image.gz-dtb" "$out/"
-  '';
-})
+}

From ff49550c7b1a118ee170b8bd96b7d59b44ae4a5e Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Thu, 1 Oct 2020 02:17:37 -0400
Subject: [PATCH 17/32] xiaomi-tissot: Update usage of kernel builder

---
 devices/xiaomi-tissot/kernel/default.nix | 30 ++++--------------------
 1 file changed, 4 insertions(+), 26 deletions(-)

diff --git a/devices/xiaomi-tissot/kernel/default.nix b/devices/xiaomi-tissot/kernel/default.nix
index 7e6fb7910..10c7f3222 100644
--- a/devices/xiaomi-tissot/kernel/default.nix
+++ b/devices/xiaomi-tissot/kernel/default.nix
@@ -1,15 +1,11 @@
 { mobile-nixos
 , fetchFromGitHub
 , kernelPatches ? []
-, dtbTool
-, buildPackages
 }:
-let inherit (buildPackages) dtc; in
-(mobile-nixos.kernel-builder-gcc6 {
+
+mobile-nixos.kernel-builder-gcc6 {
   version = "3.18.71";
   configfile = ./config.aarch64;
-  file = "Image.gz-dtb";
-  hasDTB = true;
   src = fetchFromGitHub {
     owner = "lineageos";
     repo = "android_kernel_xiaomi_msm8953";
@@ -21,24 +17,6 @@ let inherit (buildPackages) dtc; in
     ./0003-arch-arm64-Add-config-option-to-fix-bootloader-cmdli.patch
   ];
 
-  postPatch = ''
-    # Remove -Werror from all makefiles
-    local i
-    local makefiles="$(find . -type f -name Makefile)
-    $(find . -type f -name Kbuild)"
-    for i in $makefiles; do
-      sed -i 's/-Werror-/-W/g' "$i"
-      sed -i 's/-Werror//g' "$i"
-    done
-    echo "Patched out -Werror"
-  '';
-
-  makeFlags = [ "DTC_EXT=${dtc}/bin/dtc" ];
-
+  isImageGzDtb = true;
   isModular = false;
-}).overrideAttrs ({ postInstall ? "", ... }: {
-  installTargets = [ "Image.gz" "zinstall" "Image.gz-dtb" "install" ];
-  postInstall = postInstall + ''
-    cp $buildRoot/arch/arm64/boot/Image.gz-dtb $out/
-  '';
-})
+}

From 5deb826577f5d8e9ab11c851fb830ed28d5a432e Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Fri, 2 Oct 2020 19:45:58 -0400
Subject: [PATCH 18/32] asus-dumo: drop unused kernelPatches argument

---
 devices/asus-dumo/kernel/default.nix | 1 -
 1 file changed, 1 deletion(-)

diff --git a/devices/asus-dumo/kernel/default.nix b/devices/asus-dumo/kernel/default.nix
index ec0b48a60..78e150d87 100644
--- a/devices/asus-dumo/kernel/default.nix
+++ b/devices/asus-dumo/kernel/default.nix
@@ -2,7 +2,6 @@
   mobile-nixos
 , fetchFromGitHub
 , fetchgit
-, kernelPatches ? [] # FIXME
 }:
 
 mobile-nixos.kernel-builder {

From f95f5f2df80aff98ba87d5b8b3643ef4744abc2d Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Fri, 2 Oct 2020 19:46:46 -0400
Subject: [PATCH 19/32] asus-flo: drop unused kernelPatches argument

---
 devices/asus-flo/default.nix        | 2 +-
 devices/asus-flo/kernel/default.nix | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/devices/asus-flo/default.nix b/devices/asus-flo/default.nix
index 503595759..878a5df6c 100644
--- a/devices/asus-flo/default.nix
+++ b/devices/asus-flo/default.nix
@@ -16,7 +16,7 @@
   };
 
   mobile.boot.stage-1 = {
-    kernel.package = pkgs.callPackage ./kernel { kernelPatches = pkgs.defaultKernelPatches; };
+    kernel.package = pkgs.callPackage ./kernel { };
   };
 
   mobile.system.android.bootimg = {
diff --git a/devices/asus-flo/kernel/default.nix b/devices/asus-flo/kernel/default.nix
index 43d86805e..6ca88870f 100644
--- a/devices/asus-flo/kernel/default.nix
+++ b/devices/asus-flo/kernel/default.nix
@@ -1,7 +1,6 @@
 {
   mobile-nixos
 , fetchFromGitHub
-, kernelPatches ? [] # FIXME
 }:
 
 mobile-nixos.kernel-builder-gcc6 {

From 53b4c5ccd41fb691420d854030d8f202aa5270aa Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Fri, 2 Oct 2020 19:46:51 -0400
Subject: [PATCH 20/32] asus-x018d: drop unused kernelPatches argument

---
 devices/asus-x018d/default.nix        | 2 +-
 devices/asus-x018d/kernel/default.nix | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/devices/asus-x018d/default.nix b/devices/asus-x018d/default.nix
index feaa3ff7c..8e64d16a5 100644
--- a/devices/asus-x018d/default.nix
+++ b/devices/asus-x018d/default.nix
@@ -17,7 +17,7 @@
   };
 
   mobile.boot.stage-1 = {
-    kernel.package = pkgs.callPackage ./kernel { kernelPatches = pkgs.defaultKernelPatches; };
+    kernel.package = pkgs.callPackage ./kernel { };
   };
 
   mobile.system.android = {
diff --git a/devices/asus-x018d/kernel/default.nix b/devices/asus-x018d/kernel/default.nix
index a510c9a14..1353d3772 100644
--- a/devices/asus-x018d/kernel/default.nix
+++ b/devices/asus-x018d/kernel/default.nix
@@ -1,7 +1,6 @@
 {
   mobile-nixos
 , fetchFromGitHub
-, kernelPatches ? [] # FIXME
 , python2
 , buildPackages
 }:

From a3e2bfc00b115c219ad30340c0c98b8fc623ab25 Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Fri, 2 Oct 2020 19:46:58 -0400
Subject: [PATCH 21/32] asus-z00t: drop unused kernelPatches argument

---
 devices/asus-z00t/default.nix        | 2 +-
 devices/asus-z00t/kernel/default.nix | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/devices/asus-z00t/default.nix b/devices/asus-z00t/default.nix
index c2a8d3cf7..79a8a2b5b 100644
--- a/devices/asus-z00t/default.nix
+++ b/devices/asus-z00t/default.nix
@@ -19,7 +19,7 @@
   };
 
   mobile.boot.stage-1 = {
-    kernel.package = pkgs.callPackage ./kernel { kernelPatches = pkgs.defaultKernelPatches; };
+    kernel.package = pkgs.callPackage ./kernel { };
   };
 
   mobile.device.firmware = pkgs.callPackage ./firmware {};
diff --git a/devices/asus-z00t/kernel/default.nix b/devices/asus-z00t/kernel/default.nix
index 465731d79..be4d4af44 100644
--- a/devices/asus-z00t/kernel/default.nix
+++ b/devices/asus-z00t/kernel/default.nix
@@ -1,7 +1,6 @@
 {
   mobile-nixos
 , fetchFromGitHub
-, kernelPatches ? [] # FIXME
 }:
 
 mobile-nixos.kernel-builder-gcc6 {

From c3037f6bf737df21e386c33dea766474a26a7e75 Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Fri, 2 Oct 2020 19:47:07 -0400
Subject: [PATCH 22/32] google-marlin: drop unused kernelPatches argument

---
 devices/google-marlin/default.nix        | 2 +-
 devices/google-marlin/kernel/default.nix | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/devices/google-marlin/default.nix b/devices/google-marlin/default.nix
index 5a945cdcd..0027feec5 100644
--- a/devices/google-marlin/default.nix
+++ b/devices/google-marlin/default.nix
@@ -16,7 +16,7 @@
   };
 
   mobile.boot.stage-1 = {
-    kernel.package = pkgs.callPackage ./kernel { kernelPatches = pkgs.defaultKernelPatches; };
+    kernel.package = pkgs.callPackage ./kernel { };
   };
 
   mobile.system.android = {
diff --git a/devices/google-marlin/kernel/default.nix b/devices/google-marlin/kernel/default.nix
index 1e54c52e0..e32180b3c 100644
--- a/devices/google-marlin/kernel/default.nix
+++ b/devices/google-marlin/kernel/default.nix
@@ -1,7 +1,6 @@
 {
   mobile-nixos
 , fetchFromGitHub
-, kernelPatches ? [] # FIXME
 }:
 
 mobile-nixos.kernel-builder-gcc6 {

From dde7cd49611d3ffa9030d97ca151cb1571983d94 Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Fri, 2 Oct 2020 19:47:13 -0400
Subject: [PATCH 23/32] google-walleye: drop unused kernelPatches argument

---
 devices/google-walleye/default.nix        | 2 +-
 devices/google-walleye/kernel/default.nix | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/devices/google-walleye/default.nix b/devices/google-walleye/default.nix
index b774cbe0c..79f4c1153 100644
--- a/devices/google-walleye/default.nix
+++ b/devices/google-walleye/default.nix
@@ -16,7 +16,7 @@
   };
 
   mobile.boot.stage-1 = {
-    kernel.package = pkgs.callPackage ./kernel { kernelPatches = pkgs.defaultKernelPatches; };
+    kernel.package = pkgs.callPackage ./kernel { };
   };
 
   mobile.system.android = {
diff --git a/devices/google-walleye/kernel/default.nix b/devices/google-walleye/kernel/default.nix
index a8cc40c63..390950664 100644
--- a/devices/google-walleye/kernel/default.nix
+++ b/devices/google-walleye/kernel/default.nix
@@ -1,7 +1,6 @@
 {
   mobile-nixos
 , fetchFromGitHub
-, kernelPatches ? [] # FIXME
 }:
 
 mobile-nixos.kernel-builder {

From 86d08e3da2583a5f0af12cbe4e7f85d486a4752e Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Fri, 2 Oct 2020 19:47:22 -0400
Subject: [PATCH 24/32] motorola-addison: drop unused kernelPatches argument

---
 devices/motorola-addison/default.nix        | 2 +-
 devices/motorola-addison/kernel/default.nix | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/devices/motorola-addison/default.nix b/devices/motorola-addison/default.nix
index f7ebca2dc..aae797fd2 100644
--- a/devices/motorola-addison/default.nix
+++ b/devices/motorola-addison/default.nix
@@ -16,7 +16,7 @@
   };
 
   mobile.boot.stage-1 = {
-    kernel.package = pkgs.callPackage ./kernel { kernelPatches = pkgs.defaultKernelPatches; };
+    kernel.package = pkgs.callPackage ./kernel { };
   };
 
   mobile.device.firmware = pkgs.callPackage ./firmware {};
diff --git a/devices/motorola-addison/kernel/default.nix b/devices/motorola-addison/kernel/default.nix
index 14356ed6d..bb01560b2 100644
--- a/devices/motorola-addison/kernel/default.nix
+++ b/devices/motorola-addison/kernel/default.nix
@@ -2,7 +2,6 @@
   mobile-nixos
 , stdenv
 , fetchFromGitHub
-, kernelPatches ? [] # FIXME
 }:
 
 #

From f17c31ece109b1058a984ec5f4a46ad2b0e06d2d Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Fri, 2 Oct 2020 19:47:36 -0400
Subject: [PATCH 25/32] oneplus-oneplus3: drop unused kernelPatches argument

---
 devices/oneplus-oneplus3/default.nix        | 2 +-
 devices/oneplus-oneplus3/kernel/default.nix | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/devices/oneplus-oneplus3/default.nix b/devices/oneplus-oneplus3/default.nix
index 827314c98..c9a795480 100644
--- a/devices/oneplus-oneplus3/default.nix
+++ b/devices/oneplus-oneplus3/default.nix
@@ -16,7 +16,7 @@
   };
 
   mobile.boot.stage-1 = {
-    kernel.package = pkgs.callPackage ./kernel { kernelPatches = pkgs.defaultKernelPatches; };
+    kernel.package = pkgs.callPackage ./kernel { };
   };
 
   mobile.system.android.bootimg = {
diff --git a/devices/oneplus-oneplus3/kernel/default.nix b/devices/oneplus-oneplus3/kernel/default.nix
index 15db75897..61cad93d6 100644
--- a/devices/oneplus-oneplus3/kernel/default.nix
+++ b/devices/oneplus-oneplus3/kernel/default.nix
@@ -1,7 +1,6 @@
 {
   mobile-nixos
 , fetchFromGitHub
-, kernelPatches ? [] # FIXME
 }:
 
 mobile-nixos.kernel-builder-gcc6 {

From 70e7259cdc7dbd7d6b4c2f9a868c08a104672e57 Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Fri, 2 Oct 2020 19:47:47 -0400
Subject: [PATCH 26/32] pine64-pinephone-braveheart: drop unused kernelPatches
 argument

---
 devices/pine64-pinephone-braveheart/default.nix        | 2 +-
 devices/pine64-pinephone-braveheart/kernel/default.nix | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/devices/pine64-pinephone-braveheart/default.nix b/devices/pine64-pinephone-braveheart/default.nix
index 8d6397eed..a4f267d65 100644
--- a/devices/pine64-pinephone-braveheart/default.nix
+++ b/devices/pine64-pinephone-braveheart/default.nix
@@ -16,7 +16,7 @@
   };
 
   mobile.boot.stage-1 = {
-    kernel.package = pkgs.callPackage ./kernel { kernelPatches = pkgs.defaultKernelPatches; };
+    kernel.package = pkgs.callPackage ./kernel { };
   };
 
   boot.kernelParams = [
diff --git a/devices/pine64-pinephone-braveheart/kernel/default.nix b/devices/pine64-pinephone-braveheart/kernel/default.nix
index e85079f7c..601eacf13 100644
--- a/devices/pine64-pinephone-braveheart/kernel/default.nix
+++ b/devices/pine64-pinephone-braveheart/kernel/default.nix
@@ -1,7 +1,6 @@
 {
   mobile-nixos
 , fetchFromGitHub
-, kernelPatches ? [] # FIXME
 }:
 
 mobile-nixos.kernel-builder {

From 61b0145f14f0b820599450b9d8a54ec88acd6d8c Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Fri, 2 Oct 2020 19:47:56 -0400
Subject: [PATCH 27/32] sony-pioneer: drop unused kernelPatches argument

---
 devices/sony-pioneer/default.nix        | 2 +-
 devices/sony-pioneer/kernel/default.nix | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/devices/sony-pioneer/default.nix b/devices/sony-pioneer/default.nix
index 599f207c6..6cbb39de7 100644
--- a/devices/sony-pioneer/default.nix
+++ b/devices/sony-pioneer/default.nix
@@ -16,7 +16,7 @@
   };
 
   mobile.boot.stage-1 = {
-    kernel.package = pkgs.callPackage ./kernel { kernelPatches = pkgs.defaultKernelPatches; };
+    kernel.package = pkgs.callPackage ./kernel { };
   };
 
   mobile.system.android = {
diff --git a/devices/sony-pioneer/kernel/default.nix b/devices/sony-pioneer/kernel/default.nix
index 2754ad5de..c86567d7a 100644
--- a/devices/sony-pioneer/kernel/default.nix
+++ b/devices/sony-pioneer/kernel/default.nix
@@ -1,7 +1,6 @@
 {
   mobile-nixos
 , fetchFromGitHub
-, kernelPatches ? [] # FIXME
 }:
 
 mobile-nixos.kernel-builder-gcc49 {

From 7bff0070d96ea58f08bfedd232fe6e8d7710751d Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Fri, 2 Oct 2020 19:48:01 -0400
Subject: [PATCH 28/32] xiaomi-begonia: drop unused kernelPatches argument

---
 devices/xiaomi-begonia/default.nix        | 2 +-
 devices/xiaomi-begonia/kernel/default.nix | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/devices/xiaomi-begonia/default.nix b/devices/xiaomi-begonia/default.nix
index d252de483..af61054f8 100644
--- a/devices/xiaomi-begonia/default.nix
+++ b/devices/xiaomi-begonia/default.nix
@@ -19,7 +19,7 @@
   };
 
   mobile.boot.stage-1 = {
-    kernel.package = pkgs.callPackage ./kernel { kernelPatches = pkgs.defaultKernelPatches; };
+    kernel.package = pkgs.callPackage ./kernel { };
   };
 
   mobile.system.android = {
diff --git a/devices/xiaomi-begonia/kernel/default.nix b/devices/xiaomi-begonia/kernel/default.nix
index 47755e11d..97a0a1648 100644
--- a/devices/xiaomi-begonia/kernel/default.nix
+++ b/devices/xiaomi-begonia/kernel/default.nix
@@ -1,7 +1,6 @@
 {
   mobile-nixos
 , fetchFromGitHub
-, kernelPatches ? [] # FIXME
 , buildPackages
 }:
 

From 6b2482578ea1c5fad736c3d2034c5a5434057e1c Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Fri, 2 Oct 2020 19:48:07 -0400
Subject: [PATCH 29/32] xiaomi-lavender: drop unused kernelPatches argument

---
 devices/xiaomi-lavender/default.nix        | 2 +-
 devices/xiaomi-lavender/kernel/default.nix | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/devices/xiaomi-lavender/default.nix b/devices/xiaomi-lavender/default.nix
index 4acafe65b..63065ba09 100644
--- a/devices/xiaomi-lavender/default.nix
+++ b/devices/xiaomi-lavender/default.nix
@@ -19,7 +19,7 @@
   };
 
   mobile.boot.stage-1 = {
-    kernel.package = pkgs.callPackage ./kernel { kernelPatches = pkgs.defaultKernelPatches; };
+    kernel.package = pkgs.callPackage ./kernel { };
   };
 
   mobile.system.android = {
diff --git a/devices/xiaomi-lavender/kernel/default.nix b/devices/xiaomi-lavender/kernel/default.nix
index b1836082d..233f2b6e5 100644
--- a/devices/xiaomi-lavender/kernel/default.nix
+++ b/devices/xiaomi-lavender/kernel/default.nix
@@ -1,7 +1,6 @@
 {
   mobile-nixos
 , fetchFromGitHub
-, kernelPatches ? [] # FIXME
 }:
 
 #

From 0143cecfa02bfe2f72f10248e45d69ac75547ed6 Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Fri, 2 Oct 2020 19:48:15 -0400
Subject: [PATCH 30/32] xiaomi-tissot: drop unused kernelPatches argument

---
 devices/xiaomi-tissot/default.nix        | 2 +-
 devices/xiaomi-tissot/kernel/default.nix | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/devices/xiaomi-tissot/default.nix b/devices/xiaomi-tissot/default.nix
index 95513c65a..134b0be4f 100644
--- a/devices/xiaomi-tissot/default.nix
+++ b/devices/xiaomi-tissot/default.nix
@@ -16,7 +16,7 @@
   };
 
   mobile.boot.stage-1 = {
-    kernel.package = pkgs.callPackage ./kernel { kernelPatches = pkgs.defaultKernelPatches; };
+    kernel.package = pkgs.callPackage ./kernel { };
   };
 
   mobile.system.android = {
diff --git a/devices/xiaomi-tissot/kernel/default.nix b/devices/xiaomi-tissot/kernel/default.nix
index 10c7f3222..2dac464a9 100644
--- a/devices/xiaomi-tissot/kernel/default.nix
+++ b/devices/xiaomi-tissot/kernel/default.nix
@@ -1,6 +1,5 @@
 { mobile-nixos
 , fetchFromGitHub
-, kernelPatches ? []
 }:
 
 mobile-nixos.kernel-builder-gcc6 {

From 9210f716d3b9b71c57af1c08a4f61d3e29bc452c Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Fri, 2 Oct 2020 19:48:32 -0400
Subject: [PATCH 31/32] overlay: Dropped now unused defaultKernelPatches

---
 overlay/overlay.nix | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/overlay/overlay.nix b/overlay/overlay.nix
index 9a72624e7..e7be1bf1a 100644
--- a/overlay/overlay.nix
+++ b/overlay/overlay.nix
@@ -44,12 +44,6 @@ in
       ;
     };
 
-    # Default set of kernel patches.
-    defaultKernelPatches = with self.kernelPatches; [
-      bridge_stp_helper
-      p9_fixes
-    ];
-
     #
     # New software to upstream
     # ------------------------

From 36a99a3711de8d3186866179c54976834622a68d Mon Sep 17 00:00:00 2001
From: Samuel Dionne-Riel <samuel@dionne-riel.com>
Date: Fri, 2 Oct 2020 20:41:42 -0400
Subject: [PATCH 32/32] doc: Add kernel-builder documentation

---
 doc/in-depth/kernel-builder.adoc | 93 ++++++++++++++++++++++++++++++++
 1 file changed, 93 insertions(+)
 create mode 100644 doc/in-depth/kernel-builder.adoc

diff --git a/doc/in-depth/kernel-builder.adoc b/doc/in-depth/kernel-builder.adoc
new file mode 100644
index 000000000..44087933e
--- /dev/null
+++ b/doc/in-depth/kernel-builder.adoc
@@ -0,0 +1,93 @@
+= Notes about the kernel builder
+include::_support/common.inc[]
+
+The “Kernel builder” is a set of attributes available on the `mobile-nixos`
+attribute overlaid on top of Nixpkgs.
+
+```
+mobile-nixos.kernel-builder
+mobile-nixos.kernel-builder-clang_9
+mobile-nixos.kernel-builder-gcc49
+mobile-nixos.kernel-builder-gcc6
+```
+
+At the base level, they are made available pre-versioned with a
+compiler-specific `stdenv` so that OEM kernels requiring a specific compiler to
+either build or boot can use the right compiler version.
+
+The kernel builder additionally provides configuration options to work with
+common quirks in kernel builds.
+
+
+== Choosing the right builder
+
+There is no clear and fast rule for this. The most likely suggestion is to look
+at the kernel version string for a kernel built from the sources you are using.
+It should describe the compiler being used.
+
+Another way to figure out which builder to use is to compare kernel derivations
+either for devices using the same SoC. It often happens that basic quirks like
+requiring specific compilers are rooted in changes from the first party that
+forked the kernels, the SoC vendor.
+
+
+== Choosing quirks
+
+=== `isQcdt`
+
+When true, the build will use `dtbTool` to build a QCDT _device-tree image_.
+
+By default it will use the FDTs from the appropriate `arch/*/boot` folder from
+the kernel build. The directory to use can be changed using `qcdt_dtbs`.
+
+=== `isImageGzDtb`
+
+When true, the build will enable support for android-specific "Image.gz-dtb"
+appended images.
+
+It is most likely this is needed if `isQcdt` is not used for Android-based
+devices.
+
+=== `isCompressed`
+
+Set to the compression algorithm for the kernel. For the time being only `"gz"`
+or `false` are valid values. By default it is `"gz"`.
+
+=== `enableRemovingWerror`
+
+Goes through all `Makefile` files from the kernel source tree and removes the
+instances of `-Werror`.
+
+This is generally used when building a kernel with a newer compiler than which
+was used when the kernel was authored.
+
+=== `enableCompilerGcc6Quirk`
+
+When true, a `compiler-gcc6.h` is added to the expected location for the kernel
+build. This is generally only needed for older kernels.
+
+=== `enableCenteredLinuxLogo`
+
+When enabled, the kernel source will be patched to force only one instance of
+the _logo_ to be shown, and centered on the display.
+
+This is used to provide a graphical element before the stage-1 init is running.
+
+This is enabled by default. Note that on some systems the feature does not work
+even when enabled. Keep it enabled as it is a no-op.
+
+=== `enableLinuxLogoReplacement`
+
+When enabled, the file `linuxLogo224PPMFile` points at will be used to replace
+the `drivers/video/logo/logo_linux_clut224.ppm` file in the kernel source tree.
+
+This effectively replaces the Tux logo.
+
+By default an appropriate file is provided by Mobile NixOS.
+
+
+== Making a new port
+
+There is no porting guides yet. The current recommendation is to look for a
+kernel derivation from a device using the same or a similar SoC and use it as
+a starting point.