On Sat, 18 Mar 2023 at 12:16, David Gow <david...@google.com> wrote: > > As part of the Rust support for UML, we disable SSE (and similar flags) > to match the normal x86 builds. This both makes sense (we ideally want a > similar configuration to x86), and works around a crash bug with SSE > generation under Rust with LLVM. > > However, this breaks compiling stdlib.h under gcc < 11, as the x86_64 > ABI requires floating-point return values be stored in an SSE register. > gcc 11 fixes this by only doing register allocation when a function is > actually used, and since we never use atof(), it shouldn't be a problem: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99652 > > Nevertheless, only disable SSE on clang setups, as that's a simple way > of working around everyone's bugs. > > Fixes: 884981867947 ("rust: arch/um: Disable FP/SIMD instruction to match > x86") > Reported-by: Roberto Sassu <roberto.sa...@huaweicloud.com> > Link: > https://lore.kernel.org/linux-um/6df2ecef9011d85654a82acd607fdcbc93ad593c.ca...@huaweicloud.com/ > Tested-by: Roberto Sassu <roberto.sa...@huaweicloud.com> > Tested-by: SeongJae Park <s...@kernel.org> > Signed-off-by: David Gow <david...@google.com> > ---
Any chance we could get this picked up as a fix for 6.3? The UML build is still broken with older gcc versions. Cheers, -- David
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