[FFmpeg-devel] aarch64: Implement support for elf_aux_info(3) on FreeBSD and OpenBSD

[Rémi Denis-Courmont]

Le 26 juillet 2024 13:58:34 GMT+03:00, Brad Smith <brad-at-comstyle.com at ffmpeg.org> a écrit :
>aarch64: Implement support for elf_aux_info(3) on FreeBSD and OpenBSD
>
>FreeBSD 12.0+, OpenBSD -current and what will be OpenBSD 7.6 support
>elf_aux_info(3).
>
>Signed-off-by: Brad Smith <brad at comstyle.com>
>---
> configure               |  2 ++
> libavutil/aarch64/cpu.c | 23 ++++++++++++++++++++++-
> 2 files changed, 24 insertions(+), 1 deletion(-)
>
>diff --git a/configure b/configure
>index f6f5c29fea..e80b549582 100755
>--- a/configure
>+++ b/configure
>@@ -2366,6 +2366,7 @@ SYSTEM_FUNCS="
>     clock_gettime
>     closesocket
>     CommandLineToArgvW
>+    elf_aux_info
>     fcntl
>     getaddrinfo
>     getauxval
>@@ -6565,6 +6566,7 @@ check_func_headers mach/mach_time.h mach_absolute_time
> check_func_headers stdlib.h getenv
> check_func_headers sys/stat.h lstat
> check_func_headers sys/auxv.h getauxval
>+check_func_headers sys/auxv.h elf_aux_info
> check_func_headers sys/sysctl.h sysctlbyname
> 
> check_func_headers windows.h GetModuleHandle
>diff --git a/libavutil/aarch64/cpu.c b/libavutil/aarch64/cpu.c
>index cfa9306663..05272b4db4 100644
>--- a/libavutil/aarch64/cpu.c
>+++ b/libavutil/aarch64/cpu.c
>@@ -42,6 +42,27 @@ static int detect_flags(void)
>     return flags;
> }
> 
>+#elif (defined(__FreeBSD__) || defined(__OpenBSD__)) && HAVE_ELF_AUX_INFO
>+#include <stdint.h>
>+#include <sys/auxv.h>
>+
>+static int detect_flags(void)
>+{
>+    int flags = 0;
>+
>+    unsigned long hwcap = 0;
>+    elf_aux_info(AT_HWCAP, &hwcap, sizeof hwcap);
>+    unsigned long hwcap2 = 0;
>+    elf_aux_info(AT_HWCAP2, &hwcap2, sizeof hwcap2);
>+
>+    if (hwcap & HWCAP_ASIMDDP)
>+        flags |= AV_CPU_FLAG_DOTPROD;
>+    if (hwcap2 & HWCAP2_I8MM)
>+        flags |= AV_CPU_FLAG_I8MM;
>+
>+    return flags;
>+}
>+

Can't getauxval() be implemented with elf_aux_info(), or vice versa? It seems that otherwise the code should be identical to that from Linux.

> #elif defined(__APPLE__) && HAVE_SYSCTLBYNAME
> #include <sys/sysctl.h>
> 
>@@ -65,7 +86,7 @@ static int detect_flags(void)
>     return flags;
> }
> 
>-#elif defined(__OpenBSD__)
>+#elif defined(__OpenBSD__) && !HAVE_ELF_AUX_INFO
> #include <machine/armreg.h>
> #include <machine/cpu.h>
> #include <sys/types.h>