From: Mark Brown <broonie@kernel.org> commit d3e4a9d30804a78387bfcb383371209417e05c9a upstream. The top two bits of AT_HWCAP are reserved for use by glibc and the rest of the top 32 bits are being kept unallocated for potential use by glibc. Document this in the header. Signed-off-by: Mark Brown <broonie@kernel.org> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Szabolcs Nagy <szabolcs.nagy@arm.com> Link: https://lore.kernel.org/r/20220707103632.12745-2-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Qi Xi <xiqi2@huawei.com> --- arch/arm64/include/uapi/asm/hwcap.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/arm64/include/uapi/asm/hwcap.h b/arch/arm64/include/uapi/asm/hwcap.h index ff5e42430799..94869846bfef 100644 --- a/arch/arm64/include/uapi/asm/hwcap.h +++ b/arch/arm64/include/uapi/asm/hwcap.h @@ -19,6 +19,9 @@ /* * HWCAP flags - for AT_HWCAP + * + * Bits 62 and 63 are reserved for use by libc. + * Bits 32-61 are unallocated for potential use by libc. */ #define HWCAP_FP (1 << 0) #define HWCAP_ASIMD (1 << 1) -- 2.33.0