[FFmpeg-devel] [PATCH v3] libavutil/ppc: Make use of getauxval() and elf_aux_info() on ppc

[Martin Storsjö]

On Fri, 20 Sep 2024, Brad Smith wrote:

> ping.
>
> On 2024-09-15 1:40 a.m., Brad Smith wrote:
>> libavutil/ppc: Make use of getauxval() and elf_aux_info() on ppc
>> 
>> Modern Linux has getauxval() and FreeBSD/OpenBSD ppc have 
>> elf_aux_info().
>> 
>> Signed-off-by: Brad Smith <brad at comstyle.com>
>> ---
>> v2: adjust to build with older glibc.
>> v3: freebsd/ppc requires machine/cpu.h header for feature flags.
>>
>>   libavutil/ppc/cpu.c | 25 +++++++++++++++++++++++++
>>   1 file changed, 25 insertions(+)
>> 
>> diff --git a/libavutil/ppc/cpu.c b/libavutil/ppc/cpu.c
>> index 2b13cda662..9381272175 100644
>> --- a/libavutil/ppc/cpu.c
>> +++ b/libavutil/ppc/cpu.c
>> @@ -20,6 +20,11 @@
>>     #ifdef __APPLE__
>>   #include <sys/sysctl.h>
>> +#elif HAVE_GETAUXVAL || HAVE_ELF_AUX_INFO
>> +#ifdef __FreeBSD__
>> +#include <machine/cpu.h>
>> +#endif
>> +#include <sys/auxv.h>
>>   #elif defined(__linux__)
>>   #include <asm/cputable.h>
>>   #include <linux/auxvec.h>
>> @@ -56,6 +61,26 @@ int ff_get_cpu_flags_ppc(void)
>>       if (result == VECTORTYPE_ALTIVEC)
>>           return AV_CPU_FLAG_ALTIVEC;
>>       return 0;
>> +#elif HAVE_GETAUXVAL || HAVE_ELF_AUX_INFO
>> +    int flags = 0;
>> +
>> +    unsigned long hwcap = ff_getauxval(AT_HWCAP);
>> +#ifdef PPC_FEATURE2_ARCH_2_07
>> +    unsigned long hwcap2 = ff_getauxval(AT_HWCAP2);
>> +#endif
>> +
>> +    if (hwcap & PPC_FEATURE_HAS_ALTIVEC)
>> +       flags |= AV_CPU_FLAG_ALTIVEC;
>> +#ifdef PPC_FEATURE_HAS_VSX
>> +    if (hwcap & PPC_FEATURE_HAS_VSX)
>> +       flags |= AV_CPU_FLAG_VSX;
>> +#endif
>> +#ifdef PPC_FEATURE2_ARCH_2_07
>> +    if (hwcap2 & PPC_FEATURE2_ARCH_2_07)
>> +       flags |= AV_CPU_FLAG_POWER8;
>> +#endif
>> +
>> +    return flags;
>>   #elif defined(__APPLE__) || defined(__NetBSD__) || 
>> defined(__OpenBSD__)
>>   #if defined(__NetBSD__) || defined(__OpenBSD__)
>>       int sels[2] = {CTL_MACHDEP, CPU_ALTIVEC};

I don'k know much specifically about ppc, but the patch seems reasonable 
to me.

// Martin