Re: [Xenomai] xsave/xrstor compilation error

[Jean-Baptiste Tredez <jean-baptiste.tredez@basystemes.fr>]

On 24/10/2013 19:26, Jan Kiszka wrote :
> On 2013-10-24 17:40, Jan Kiszka wrote:
>> On 2013-10-24 16:48, Gilles Chanteperdrix wrote:
>>> On 10/24/2013 12:06 PM, Jan Kiszka wrote:
>>>> We
>>>> can, of course, replace the instructions with their obcodes (like the
>>>> kernel does), just makes the code more ugly.
>>> Jan, please do this, even if it makes the code more ugly, it makes sense
>>> for the 2.6.3 release to continue working with the tools it already
>>> supported. No question for -forge, but we try hard to keep ABI
>>> compatibility so that users can upgrade xenomai without even recompiling
>>> their application, it does not make sense to suddenly stop working with
>>> a toolchain which always worked before.
>> In fact, we already have legacy gas support: all these new instructions
>> are wrapped with CONFIG_AS_AVX, and only if that is set we use the new
>> assembler instructions. Given that this CONFIG has to be set based on
>> some test, something seems to go wrong in the kernel build over there.
>> But that's outside of the Xenomai scope. I'm currently trying to find
>> out if there was some related kernel issue back then.
> OK, something likely went wrong in my brain back then while I tried to
> make this build for all the combinations. I can't recall what those
> CONFIG_X86_64 tests were for. This should build and in theory also work:
>
> diff --git a/include/asm-x86/bits/pod.h b/include/asm-x86/bits/pod.h
> index a32575f..c6fbcee 100644
> --- a/include/asm-x86/bits/pod.h
> +++ b/include/asm-x86/bits/pod.h
> @@ -241,7 +241,7 @@ static inline void __save_i387(x86_fpustate *fpup)
>   {
>   #ifdef cpu_has_xsave
>   	if (cpu_has_xsave) {
> -#if defined(CONFIG_AS_AVX) || !defined CONFIG_X86_64
> +#if defined(CONFIG_AS_AVX)
>   		asm volatile("xsave" XSAVE_SUFFIX " %0"
>   			     : "=m" (fpup->xsave) : "a" (-1), "d" (-1)
>   			     : "memory");
> @@ -301,7 +301,7 @@ static inline void __restore_i387(x86_fpustate *fpup)
>   {
>   #ifdef cpu_has_xsave
>   	if (cpu_has_xsave) {
> -#if defined(CONFIG_AS_AVX) || !defined(CONFIG_X86_64)
> +#if defined(CONFIG_AS_AVX)
>   		asm volatile("xrstor" XSAVE_SUFFIX " %0"
>   			     : : "m" (fpup->xsave), "a" (-1), "d" (-1)
>   			     : "memory");
>
> Jean-Baptiste, do you happen to have an xsave-capable box at hand to
> test this (/proc/cpuinfo shows the available features)? Xenomai's
> switchtest will stress the code.
>
> Thanks,
> Jan
>

No, I do not have an xsave-capable box (no xsave or avx flag, only fxsr).
This patch works fine here.

Jean-Baptiste