[PATCH 2/3] nptl: Do not always assume set_robust_list availability (BZ 33225)

[Andreas K. Huettel]

Am Mittwoch, 30. Juli 2025, 08:41:09 Mitteleuropäische Sommerzeit schrieb Andreas Schwab:
> On Jul 29 2025, Florian Weimer wrote:
> 
> > I'm not sure this is the right direction.  Is qemu-user compatibility
> > that important to users?
> 
> For example, openSUSE Tumbleweed for RISC-V is built completely with
> qemu user-space emulation (we don't have this issue right now since our
> glibc is built with the default minimum kernel that still enables the
> runtime check).

Gentoo does the rolling stage builds [1] for the following architectures
with qemu-user:

alpha, loong, mips (all variants), m68k, riscv (all variants), sparc (64bit)

Using Adhemerval's getdents64/dir filepos patches [2], that works overall
very reliably (for years now).

Where it doesn't work (due to qemu) at the moment (from memory):
 * hppa
 * sparc 32bit (problems somewhere in filesystem support, bash suddenly
   complains about abruptly ending scripts or memory corruption)
 * weird things are happening on old-style m68k occasionally, but -malign-int
   m68k is much more stable
 * mips 32bit, riscv 32bit, m68k with musl (python build hangs)

If something breaks, that's usually at first the Python build (which seems
to do extensive multithreading).


[1] https://www.gentoo.org/downloads/
[2] https://gitweb.gentoo.org/proj/toolchain/glibc-patches.git/tree/9999 patches 4-6


> 
> FWIW, the other big problem for qemu user-space emulation is posix_spawn
> because the emulation does not implement a true CLONE_VFORK (it emulates
> it with fork).  This breaks situations where there are errors in the
> child process until and including execve; that failure cannot be
> communicated back to the parent process.
> 
> 


-- 
Andreas K. Hüttel
dilfridge@gentoo.org
Gentoo Linux developer
(council, toolchain, base-system, perl, libreoffice)
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