[PATCH] arm64: Document SVE constraints on new hwcaps

[PATCH] arm64: Document SVE constraints on new hwcaps

[Mark Brown]

Two of the SVE hwcaps added for the SVE features in the 2025 dpISA did
not explicitly call out their dependency on SVE in the ABI documentation.
Do so.

While we're here reorder the SVE and fature specific ID registers for
HWCAP3_SVE_LUT6 which did have the SVE dependency but listed it second
unlike the other SVE specific ID registers.

Fixes: abca5e69ab626 ("arm64/cpufeature: Define hwcaps for 2025 dpISA features")
Reported-by: Will Deacon <will@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 Documentation/arch/arm64/elf_hwcaps.rst | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/Documentation/arch/arm64/elf_hwcaps.rst b/Documentation/arch/arm64/elf_hwcaps.rst
index 07ff9ea1d605..f60ca5612daa 100644
--- a/Documentation/arch/arm64/elf_hwcaps.rst
+++ b/Documentation/arch/arm64/elf_hwcaps.rst
@@ -452,10 +452,12 @@ HWCAP3_LS64
     memory location, otherwise fallback to the non-atomic alternatives.
 
 HWCAP3_SVE_B16MM
-    Functionality implied by ID_AA64ZFR0_EL1.B16B16 == 0b0011
+    Functionality implied by ID_AA64PFR0_EL1.SVE == 0b0001 and
+    ID_AA64ZFR0_EL1.B16B16 == 0b0011
 
 HWCAP3_SVE2P3
-    Functionality implied by ID_AA64ZFR0_EL1.SVEver == 0b0100
+    Functionality implied by ID_AA64PFR0_EL1.SVE == 0b0001 and
+    ID_AA64ZFR0_EL1.SVEver == 0b0100
 
 HWCAP3_SME_LUT6
     Functionality implied by ID_AA64SMFR0_EL1.LUT6 == 0b1
@@ -473,8 +475,9 @@ HWCAP3_F16F32MM
     Functionality implied by ID_AA64ISAR0_EL1.FHM == 0b0011
 
 HWCAP3_SVE_LUT6
-    Functionality implied by ID_AA64ISAR2_EL1.LUT == 0b0010 and
-    ID_AA64PFR0_EL1.SVE == 0b0001.
+    Functionality implied by ID_AA64PFR0_EL1.SVE == 0b0001 and
+    ID_AA64ISAR2_EL1.LUT == 0b0010.
+
 
 4. Unused AT_HWCAP bits
 -----------------------

---
base-commit: abca5e69ab6268cbe1913b19da5a98c3383f8bb3
change-id: 20260522-arm64-elf-hwcaps-sve-cleanup-1af7874ad5b7

Best regards,
--  
Mark Brown <broonie@kernel.org>

Re: [PATCH] arm64: Document SVE constraints on new hwcaps

[Will Deacon]

On Fri, 22 May 2026 18:50:28 +0100, Mark Brown wrote:
> Two of the SVE hwcaps added for the SVE features in the 2025 dpISA did
> not explicitly call out their dependency on SVE in the ABI documentation.
> Do so.
> 
> While we're here reorder the SVE and fature specific ID registers for
> HWCAP3_SVE_LUT6 which did have the SVE dependency but listed it second
> unlike the other SVE specific ID registers.
> 
> [...]

Applied to arm64 (for-next/cpufeature), thanks!

[1/1] arm64: Document SVE constraints on new hwcaps
      https://git.kernel.org/arm64/c/f20f8fe086b2

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev