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Re: [PATCH] powerpc: Fix TLE build for SPE (BZ #22926)
- From: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
- To: libc-alpha at sourceware dot org
- Date: Tue, 6 Mar 2018 15:37:49 -0300
- Subject: Re: [PATCH] powerpc: Fix TLE build for SPE (BZ #22926)
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On 05/03/2018 15:17, Adhemerval Zanella wrote:
> Some SPE opcodes clashes with some recent PowerISA opcodes and
> until recently gas did not complain about it. However binutils
> recently changed it and now VLE configured gas does not support to
> assembler some instruction that might class with VLE (HTM for
> instance). It also does not help that glibc build hardware lock
> elision support as default (regardless of assembler support).
> Although runtime will not actually enables TLE on SPE hardware
> (since kernel will not advertise it), I see little advantage on
> adding HTM support on SPE built glibc. SPE uses an incompatible
> ABI which does not allow share the same build with default
> powerpc and HTM code slows down SPE without any benefict.
> This patch fixes it by only building HTM when SPE configuration
> is not used.
> Checked with a powerpc-linux-gnuspe build. I also did some sniff
> tests on a e500 hardware without any issue.
I also saw no regression compared to PowerPC (32-bit soft-float) report
for 2.27  on a e500 hardware.