add support for mips(el)-unknown-linux-musl #31298

japaric · Jan 30, 2016

This target covers MIPS devices that run the trunk version of OpenWRT.

The x86_64-unknown-linux-musl target always links statically to C libraries. For
the mips(el)-unknown-linux-musl target, we opt for dynamic linking (like most of
other targets do) to keep binary size down.

As for the C compiler flags used in the build system, we use the same flags used
for the mips(el)-unknown-linux-gnu target.

r? @alexcrichton

japaric · Jan 30, 2016

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japaric · Jan 30, 2016

.gitmodules

@@ -16,4 +16,5 @@
 	url = https://github.com/rust-lang/rust-installer.git
 [submodule "src/liblibc"]
 	path = src/liblibc
-	url = https://github.com/rust-lang-nursery/libc.git
+	url = https://github.com/japaric/libc.git


TODO revert this change

japaric · Jan 30, 2016

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japaric · Jan 30, 2016

mk/cfg/mips-unknown-linux-musl.mk

@@ -0,0 +1,24 @@
+# mips-unknown-linux-musl configuration
+CC_mips-unknown-linux-musl=mips-openwrt-linux-gcc


TODO change the prefixes to something vendor neutral. Probably mips-linux-musl-gcc.

japaric · Jan 30, 2016

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japaric · Jan 30, 2016

src/liblibc

@@ -1 +1 @@
-Subproject commit 91ff43c736de664f8d3cd351e148c09cdea6731e
+Subproject commit 81c05bcddb05d0e5facf66f3945405bbf50b04d3


TODO this will need to be updated

japaric · Jan 30, 2016

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japaric · Jan 30, 2016

src/libstd/os/linux/raw.rs

@@ -93,11 +93,20 @@ mod arch {
    use os::raw::{c_long, c_ulong};
    use os::unix::raw::{gid_t, uid_t};

+    #[cfg(target_env = "musl")]
+    #[stable(feature = "raw_ext", since = "1.1.0")] pub type blkcnt_t = i64;


I'm not sure what stability level this should have. AFAIK, these types are going to be deprecated in the future.

Ah yeah these are fine to stay as-is

alexcrichton · Jan 30, 2016

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alexcrichton · Jan 30, 2016

src/librustc_back/target/mipsel_unknown_linux_musl.rs

+        llvm_target: "mipsel-unknown-linux-musl".to_string(),
+        target_endian: "little".to_string(),
+        target_pointer_width: "32".to_string(),
+        arch: "mips".to_string(),


Should this be mipsel?

Should this be mipsel?

Not sure! The existing mipsel-unknown-linux-gnu target is also using mips as the arch.

AIUI, this arch field is used for #[cfg(target_arch = ...)] and not for codegen (that's what llvm-target is used for). If we want to change both targets (mipsel-gnu and mipsel-musl) to use arch = mipsel, then we'll have to update the cfgs in crates like libc from #[cfg(target_arch = "mips")] to #[cfg(any(target_arch = "mips", any(target_arch = "mipsel"))].

Oh interesting! That may be a bug in the target triple, however, depending on how you look at it. Either that or we may just want to make sure that we're consistent. Some data points:

The newly-added powerpc64le-unknown-linux-gnu triple has powerpc64le as the target_arch.

There's some cfg(target_arch = "mipsel") directives in the standard library, which apparently are doing nothing.

We don't necessarily require the arch in the triple to equal the arch in target_arch, for example armv7 recently added has the target_arch of arm.

I think that I'd prefer to lean towards leaving this as mips and tweaking the powerpc64le triple to have powerpc64 as the target_arch. That seems the most consistent to me and also the most ergonomic. The two triples can still be differentiated by looking at target_endian

I think that I'd prefer to lean towards leaving this as mips and tweaking the powerpc64le triple to have powerpc64 as the target_arch. That seems the most consistent to me and also the most ergonomic. The two triples can still be differentiated by looking at target_endian

👍 from me

alexcrichton · Jan 30, 2016

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alexcrichton · Jan 30, 2016

mk/cfg/mipsel-unknown-linux-musl.mk

+CC_mipsel-unknown-linux-musl=mipsel-openwrt-linux-gcc
+CXX_mipsel-unknown-linux-musl=mipsel-openwrt-linux-g++
+CPP_mipsel-unknown-linux-musl=mipsel-openwrt-linux-gcc
+AR_mipsel-unknown-linux-musl=mipsel-openwrt-linux-ar


This should also work with a standard mipsel-linux-gnu-gcc toolchain, right?

Oh, I see your TODO above

alexcrichton · Jan 30, 2016

Looks good to me, thanks @japaric!

This brings up an interesting facet about the MUSL targets, however, about whether the C standard library is statically or dynamically linked. The x86_64-unknown-linux-musl target was originally created with the intention of only really being used for statically linked binaries. I'd personally prefer that these targets remain consistent, but it seems that the current primary use case (OpenWRT?) is dynamically linking the C standard library.

In that sense all of the MUSL targets should really support either dynamically linking or statically linking, but we don't really support this sort of lazy linkage in the standard library (only on crates.io where you build from source).

I think for now I'd be fine basically choosing "whatever seems best" for the target at hand (e.g. static for x86_64 and perhaps i686 but dynamic for mips), but it's something we may wish to reconsider in the future.

alexcrichton · Jan 30, 2016

ah and of course cc @rust-lang/tools about the dynamic-vs-static linkage of musl

japaric · Jan 30, 2016

This is now merge ready.

alexcrichton · Jan 30, 2016

@bors: r+ 64ac041

bors · Jan 30, 2016

⌛️ Testing commit 64ac041 with merge 8110338...

bors · Jan 30, 2016

💔 Test failed - auto-linux-musl-64-opt

japaric · Jan 31, 2016

The failed test (os::raw::tests::unix) was caused by rust-lang/libc#122 which changed the definition of nlink_t to usize. I'll send a PR to libc to restore the old definition.

japaric · Jan 31, 2016

@bors: r=alexcrichton 27127db

bors · Jan 31, 2016

⌛️ Testing commit 27127db with merge 9041b93...

bors · Jan 31, 2016

☀️ Test successful - auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-64-debug-opt, auto-linux-64-nopt-t, auto-linux-64-opt, auto-linux-64-x-android-t, auto-linux-cross-opt, auto-linux-musl-64-opt, auto-mac-32-opt, auto-mac-64-nopt-t, auto-mac-64-opt, auto-mac-ios-opt, auto-win-gnu-32-nopt-t, auto-win-gnu-32-opt, auto-win-gnu-64-nopt-t, auto-win-gnu-64-opt, auto-win-msvc-32-opt, auto-win-msvc-64-opt

alexcrichton self-assigned this Jan 30, 2016

japaric changed the title ~~[blocked] add support for mips(el)-unknown-linux-musl~~ add support for mips(el)-unknown-linux-musl Jan 30, 2016

japaric added some commits Jan 30, 2016

revert changes used for local testing

146dfce

rustc: set MIPS cpu/features in the compiler
cf #31303

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64ac041

japaric force-pushed the japaric:mips-musl branch from 84c1574 to 64ac041 Jan 30, 2016

alexcrichton referenced this pull request Jan 30, 2016
Merged
Remove "powerpc64le" and "mipsel" target_arch #31312

japaric referenced this pull request Jan 31, 2016
Merged
musl: define nlink_t as u32/u64 #165

update libc submodule
fixes failed test (std::os::raw::tests::unix) in x86_64-musl target

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27127db

bors referenced this pull request Jan 31, 2016
Closed
move middle::check_match and middle::const_eval to their own crate #31255

bors merged commit 27127db into rust-lang:master Jan 31, 2016
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Closed
std: Move pc-windows-gnu to SEH-based unwinding #31313

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Merged
Add Illumos support #31078

japaric deleted the japaric:mips-musl branch Jan 31, 2016

malbarbo referenced this pull request Jan 22, 2018
Merged
Do not assume dynamic linking for musl/mips[el] targets #47663

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japaric changed the title [blocked] add support for mips(el)-unknown-linux-musl add support for mips(el)-unknown-linux-musl Jan 30, 2016

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