Re: [FFmpeg-devel] [PATCH] avutil: [LA] use getauxval to do runtime check.

[Shiyou Yin <yinshiyou-hf@loongson.cn>]

> 2023年2月23日 15:48，Steven Liu <lingjiujianke@gmail.com> 写道：
> 
> Shiyou Yin <yinshiyou-hf@loongson.cn> 于2023年2月14日周二 20:26写道：
>> 
>> Replace cpucfg with getauxval to avoid crash in case of
>> some processor capabilities are not supportted by kernel used.
>> ---
>> libavutil/loongarch/cpu.c | 24 ++++++++----------------
>> 1 file changed, 8 insertions(+), 16 deletions(-)
>> 
>> diff --git a/libavutil/loongarch/cpu.c b/libavutil/loongarch/cpu.c
>> index e4b240bc44..cad8504fde 100644
>> --- a/libavutil/loongarch/cpu.c
>> +++ b/libavutil/loongarch/cpu.c
>> @@ -21,26 +21,18 @@
>> 
>> #include <stdint.h>
>> #include "cpu.h"
>> +#include <sys/auxv.h>
>> 
>> -#define LOONGARCH_CFG2 0x2
>> -#define LOONGARCH_CFG2_LSX    (1 << 6)
>> -#define LOONGARCH_CFG2_LASX   (1 << 7)
>> -
>> -static int cpu_flags_cpucfg(void)
>> +#define LA_HWCAP_LSX    (1<<4)
>> +#define LA_HWCAP_LASX   (1<<5)
>> +static int cpu_flags_getauxval(void)
>> {
>>     int flags = 0;
>> -    uint32_t cfg2 = 0;
>> -
>> -    __asm__ volatile(
>> -        "cpucfg %0, %1 \n\t"
>> -        : "+&r"(cfg2)
>> -        : "r"(LOONGARCH_CFG2)
>> -    );
>> +    int flag  = (int)getauxval(AT_HWCAP);
>> 
>> -    if (cfg2 & LOONGARCH_CFG2_LSX)
>> +    if (flag & LA_HWCAP_LSX)
>>         flags |= AV_CPU_FLAG_LSX;
>> -
>> -    if (cfg2 & LOONGARCH_CFG2_LASX)
>> +    if (flag & LA_HWCAP_LASX)
>>         flags |= AV_CPU_FLAG_LASX;
>> 
>>     return flags;
>> @@ -49,7 +41,7 @@ static int cpu_flags_cpucfg(void)
>> int ff_get_cpu_flags_loongarch(void)
>> {
>> #if defined __linux__
>> -    return cpu_flags_cpucfg();
>> +    return cpu_flags_getauxval();
>> #else
>>     /* Assume no SIMD ASE supported */
>>     return 0;
>> --
>> 2.20.1
>> 
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>> 
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> 
> 
> LGTM
> 
> Thanks
> Steven
> _______________________________________________

Could you please help to merge this patch.
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