From: Mark Brown <broonie@kernel.org>
To: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>,
Szabolcs Nagy <szabolcs.nagy@arm.com>,
linux-arm-kernel@lists.infradead.org,
Mark Brown <broonie@kernel.org>
Subject: [PATCH v4 1/3] arm64/hwcap: Document allocation of upper bits of AT_HWCAP
Date: Wed, 6 Jul 2022 18:52:54 +0100 [thread overview]
Message-ID: <20220706175256.847703-2-broonie@kernel.org> (raw)
In-Reply-To: <20220706175256.847703-1-broonie@kernel.org>
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>
---
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 4bb2cc8ac446..cc2ccd0a9edf 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 60 and 61 are reserved for use by libc.
+ * Bits 32-59 are unallocated for potential use by libc.
*/
#define HWCAP_FP (1 << 0)
#define HWCAP_ASIMD (1 << 1)
--
2.30.2
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next prev parent reply other threads:[~2022-07-06 17:55 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-06 17:52 [PATCH v4 0/3] arm64: Start allocating upper bits of AT_HWCAP2 Mark Brown
2022-07-06 17:52 ` Mark Brown [this message]
2022-07-07 9:00 ` [PATCH v4 1/3] arm64/hwcap: Document allocation of upper bits of AT_HWCAP Szabolcs Nagy
2022-07-06 17:52 ` [PATCH v4 2/3] arm64/cpufeature: Store elf_hwcaps as a bitmap rather than unsigned long Mark Brown
2022-07-06 17:52 ` [PATCH v4 3/3] arm64/hwcap: Support FEAT_EBF16 Mark Brown
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