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

[James Clarke <jrtc27 at jrtc27 dot com>]

On Wed, Mar 07, 2018 at 01:50:27PM -0300, Adhemerval Zanella wrote:
>
>
> On 06/03/2018 15:37, Adhemerval Zanella wrote:
> >
> >
> > 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
> >
>
> If no one opposes I will commit it this shortly.

Hi Adhemerval,
I just tested this myself (by dropping it into the currently-failing
Debian package) and it built successfully, so please go ahead.

Thanks,
James