Docs: Improve documentation and add QEMU generation script

BootLoader/bin/BootInstall.command

@@ -1,5 +1,7 @@
 #!/bin/bash
 
+# Install booter on physical disk.
+
 cd "$(dirname "$0")"
 diskutil list
 echo "Enter disk number to install to:"

BootLoader/bin/QemuBuild.command

@@ -0,0 +1,75 @@
+#!/bin/bash
+
+# Build QEMU image, example:
+# qemu-system-x86_64 -drive file=$QEMU_IMAGE/OpenCore.RO.raw -serial stdio \
+#   -usb -device usb-kbd -device usb-mouse -s -m 8192
+
+cd "$(dirname "$0")"
+
+if [ "$(which qemu-img)" = "" ]; then
+  echo "QEMU installation missing"
+  exit 1
+fi
+
+if [ ! -d ROOT ]; then
+  echo "No ROOT directory with ESP partition contents"
+  exit 1
+fi
+
+rm -f OpenCore.dmg.sparseimage OpenCore.RO.raw OpenCore.RO.dmg
+hdiutil create -size 200m  -layout "UNIVERSAL HD"  -type SPARSE  -o OpenCore.dmg
+newDevice=$(hdiutil attach -nomount OpenCore.dmg.sparseimage )
+newDevice=$(echo $newDevice | awk  '{print $1}')
+echo $newDevice
+
+diskutil partitionDisk $newDevice 1 MBR fat32 TEST R
+
+# boot install script
+diskutil list
+N=$(echo $newDevice | tr -dc '0-9')
+echo $N
+
+
+if [[ ! $(diskutil info disk${N} |  sed -n 's/.*Device Node: *//p') ]]
+then
+  echo Disk $N not found
+  exit
+fi
+
+FS=$(diskutil info disk${N}s1 | sed -n 's/.*File System Personality: *//p')
+echo $FS
+
+if [ "$FS" != "MS-DOS FAT32" ]
+then
+  echo "No FAT32 partition to install"
+  exit
+fi
+
+# Write MBR
+sudo fdisk -f boot0 -u /dev/rdisk${N}
+
+diskutil umount disk${N}s1
+sudo dd if=/dev/rdisk${N}s1 count=1  of=origbs
+cp -v boot1f32 newbs
+sudo dd if=origbs of=newbs skip=3 seek=3 bs=1 count=87 conv=notrunc
+dd if=/dev/random of=newbs skip=496 seek=496 bs=1 count=14 conv=notrunc
+sudo dd if=newbs of=/dev/rdisk${N}s1
+diskutil mount disk${N}s1
+
+cp -v boot "$(diskutil info  disk${N}s1 |  sed -n 's/.*Mount Point: *//p')"
+cp -rv ROOT/* "$(diskutil info  disk${N}s1 |  sed -n 's/.*Mount Point: *//p')"
+
+if [ $(diskutil info  disk${N} |  sed -n 's/.*Content (IOContent): *//p') == "FDisk_partition_scheme" ]
+then
+sudo fdisk -e /dev/rdisk$N <<-MAKEACTIVE
+p
+f 1
+w
+y
+q
+MAKEACTIVE
+fi
+
+hdiutil detach $newDevice
+hdiutil convert -format UDRO OpenCore.dmg.sparseimage -o OpenCore.RO.dmg 
+qemu-img convert -f dmg -O raw OpenCore.RO.dmg OpenCore.RO.raw

BootLoader/boot1f32.nasm

@@ -182,7 +182,7 @@ gExtInfo            times   25  db  0
 gFileName           db      "BOOT       " ; Used as a magic string in boot0
 
 ;--------------------------------------------------------------------------
-; Boot code is loaded at 0:7C00h.
+; Boot code is loaded at 0:E000h.
 ;
 start:
     ;

README.md

@@ -15,6 +15,30 @@ Acidanthera variant of DuetPkg. Specialties:
 - Always loads from bootstrapped volume first.
 - Some changes inherited from Clover EFI bootloader.
 
+## Simplified bootstrap process
+
+1. `boot0` is loaded by BIOS from MBR at `7C00h`.
+2. `boot0` finds active MBR or ESP GPT partition.
+3. `boot0` loads `boot1` from found partition at `9000h`.
+4. `boot1` finds `boot` file at partition root.
+5. `boot1` loads `boot` at `20000h` (begins with `StartX64` or `StartIA32`).
+6. `Start` enables paging (prebuilt for `X64` or generated for `IA32`).
+7. `Start` switches to native CPU mode (`X64` or `IA32`) with paging.
+8. `Start` jumps to concatentated `EfiXX` at `21000h` (`Efi64` or `Efi32`).
+9. `EfiXX` loads `EfiLdr` (concatenated after `EfiXX`) at `10000h`.
+10. `EfiLdr` decompresses and maps `DUETFV`, `DxeIpl`, `DxeCore`.
+11. `EfiLdr` jumps to `DxeIpl`, which starts `DxeCore` from `DUETFV`.
+12. `DxeCore` starts BDS, which loads `EFI/OC/OpenCore.efi`.
+
+| Name      | PHYS        | VIRT        |
+|:----------|:------------|:------------|
+| `boot0`   | `7C00h`     |             |
+| `boot1`   | `9000h`     |             |
+| `Start`   | `20000h`    | `20000h`    |
+| `EfiXX`   | `21000h`    | `21000h`    |
+| `EfiLdr`  | `22000h`    | `10000h`    |
+| `DxeIpl`+ | `22000h+`   | `???`       |
+
 ## Error codes
 
 - `BOOT MISMATCH!` - Bootstrap partition signature identification failed.