[ruby-core:96601] [Ruby master Bug#16455] coroutine ucontext uses deprecated POSIX getcontext/swapcontext/makecontext, absent in musl

[luizluca@gmail.com]

Issue #16455 has been updated by luizluca (Luiz Angelo Daros de Luca).


nobu (Nobuyoshi Nakada) wrote:
> luizluca (Luiz Angelo Daros de Luca) wrote:
> > I tried to disable it with --without-coroutine, --with-out-coroutine and --with-coroutine=no, but it is innocuous or try to use a "no" implementation.
> 
> Does `—-with-coroutine=copy` work?

Yes. And it also affects uclibc.

autoconf should test for getcontext/swapcontext/makecontext at link time as musl do have them declared (but not implemented). uclibc fails even before, while building as it does not even declare them.

For those cases, copy might work.

----------------------------------------
Bug #16455: coroutine ucontext uses deprecated POSIX getcontext/swapcontext/makecontext, absent in musl
https://bugs.ruby-lang.org/issues/16455#change-83568

* Author: luizluca (Luiz Angelo Daros de Luca)
* Status: Open
* Priority: Normal
* Assignee: ioquatix (Samuel Williams)
* Target version: 
* ruby -v: ruby 2.7.0p0 (2019-12-25 revision 647ee6f091)
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
Hello,

While building ruby 2.7.0 for mips with musl, it fails:


```
linking miniruby                                                                                   /home/luizluca/prog-local/openwrt/trunk/staging_dir/toolchain-mips_24kc_gcc-8.3.0_musl/lib/gcc/mips-openwrt-linux-musl/8.3.0/../../../../mips-openwrt-linux-musl/bin/ld: cont.o: in function `coroutine_initialize_main':                                                                                cont.c:(.text+0x36c): undefined reference to `getcontext'                                          /home/luizluca/prog-local/openwrt/trunk/staging_dir/toolchain-mips_24kc_gcc-8.3.0_musl/lib/gcc/mips-openwrt-linux-musl/8.3.0/../../../../mips-openwrt-linux-musl/bin/ld: cont.o: in function `fiber_setcontext':                                                                                         cont.c:(.text+0xde6): undefined reference to `swapcontext'                                         /home/luizluca/prog-local/openwrt/trunk/staging_dir/toolchain-mips_24kc_gcc-8.3.0_musl/lib/gcc/mips-openwrt-linux-musl/8.3.0/../../../../mips-openwrt-linux-musl/bin/ld: cont.o: in function `fiber_switch':                                                                                             cont.c:(.text+0x16b8): undefined reference to `makecontext'                                        collect2: error: ld returned 1 exit status                                                         make[3]: *** [Makefile:271: miniruby] Error 1
```

It seems that now ruby either uses native ASM code or ucontext for coroutine.
Both are unavailable in my crossbuild. It was building and running with 2.6.x:

```
configure:25935: checking native coroutine implementation for mips-linux-gnu                       configure:25976: result: no
```

With 2.7.0:

```
configure:26536: checking native coroutine implementation for mips-linux-gnu                       configure:26601: result: ucontext
```

I tried to disable it with --without-coroutine, --with-out-coroutine and --with-coroutine=no, but it is innocuous or try to use a "no" implementation.

It looks like this introduced the change https://github.com/ruby/ruby/commit/7291fef55c90b9ab6b3c22018b16972861b98c9d

And musl might never fix it:
https://wiki.musl-libc.org/open-issues.html





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