Re: [PATCH 3/7] util/cpuinfo-aarch64: Detect FEAT_CSSC

[Brad Smith <brad@comstyle.com>]

On 2026-08-11 8:31 p.m., Richard Henderson wrote:
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   host/include/aarch64/host/cpuinfo.h |  1 +
>   util/cpuinfo-aarch64.c              | 13 ++++++++++++-
>   2 files changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/host/include/aarch64/host/cpuinfo.h b/host/include/aarch64/host/cpuinfo.h
> index fe671534e4..c32c04dade 100644
> --- a/host/include/aarch64/host/cpuinfo.h
> +++ b/host/include/aarch64/host/cpuinfo.h
> @@ -12,6 +12,7 @@
>   #define CPUINFO_AES             (1u << 3)
>   #define CPUINFO_PMULL           (1u << 4)
>   #define CPUINFO_BTI             (1u << 5)
> +#define CPUINFO_CSSC            (1u << 6)
>   
>   /* Initialized with a constructor. */
>   extern unsigned cpuinfo;
> diff --git a/util/cpuinfo-aarch64.c b/util/cpuinfo-aarch64.c
> index 288074c08f..0b4f8a747d 100644
> --- a/util/cpuinfo-aarch64.c
> +++ b/util/cpuinfo-aarch64.c
> @@ -72,6 +72,7 @@ unsigned __attribute__((constructor)) cpuinfo_init(void)
>   
>       unsigned long hwcap2 = qemu_getauxval(AT_HWCAP2);
>       info |= (hwcap2 & HWCAP2_BTI ? CPUINFO_BTI : 0);
> +    info |= (hwcap2 & HWCAP2_CSSC ? CPUINFO_CSSC : 0);
>   #endif
>   #ifdef CONFIG_DARWIN
>       info |= sysctl_for_bool("hw.optional.arm.FEAT_LSE") * CPUINFO_LSE;
> @@ -79,10 +80,11 @@ unsigned __attribute__((constructor)) cpuinfo_init(void)
>       info |= sysctl_for_bool("hw.optional.arm.FEAT_AES") * CPUINFO_AES;
>       info |= sysctl_for_bool("hw.optional.arm.FEAT_PMULL") * CPUINFO_PMULL;
>       info |= sysctl_for_bool("hw.optional.arm.FEAT_BTI") * CPUINFO_BTI;
> +    info |= sysctl_for_bool("hw.optional.arm.FEAT_CSSC") * CPUINFO_CSSC;
>   #endif
>   #if defined(__OpenBSD__) && !defined(CONFIG_ELF_AUX_INFO)
>       int mib[2];
> -    uint64_t isar0;
> +    uint64_t isar0, isar2;
>       uint64_t pfr1;
>       size_t len;
>   
> @@ -101,6 +103,15 @@ unsigned __attribute__((constructor)) cpuinfo_init(void)
>           }
>       }
>   
> +    mib[0] = CTL_MACHDEP;
> +    mib[1] = CPU_ID_AA64ISAR2;
> +    len = sizeof(isar2);
> +    if (sysctl(mib, 2, &isar2, &len, NULL, 0) != -1) {
> +        if (ID_AA64ISAR2_CSSC(isar2) >= ID_AA64ISAR2_CSSC_IMPL) {
> +            info |= CPUINFO_CSSC;
> +        }
> +    }
> +
>       mib[0] = CTL_MACHDEP;
>       mib[1] = CPU_ID_AA64PFR1;
>       len = sizeof(pfr1);

You can remove the bottom chunk. Any OpenBSD release that has the 
ID_AA64ISAR2_CSSC
and ID_AA64ISAR2_CSSC_IMPL constants is also covered by elf_aux_info() 
which is the
first chunk.

ID_AA64ISAR2_CSSC_IMPL