Re: [PATCH] powerpc: Fix TLE build for SPE (BZ #22926)

[Adhemerval Zanella <adhemerval dot zanella at linaro dot org>]

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 [1] on a e500 hardware.

[1] https://sourceware.org/glibc/wiki/Release/2.27#PowerPC_.2832-bit_soft-float.29