[PATCH] arm64: cpucaps: Remove stale comment about keeping capabilities sorted

[PATCH] arm64: cpucaps: Remove stale comment about keeping capabilities sorted

[Will Deacon]

From: Will Deacon <willdeacon@google.com>

There is no functional requirement to keep the entries in arm64's
tools/cpucaps file sorted alphabetically and, in fact, they have fallen
out of order over time. Given that only the arm64 tree touches this file,
just remove the stale comment and accept that we're collectively not
very good at the alphabet.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Reported-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
---

Follow-up from the discussion at:

https://lore.kernel.org/r/20260519092243.7278-1-will@kernel.org

 arch/arm64/tools/cpucaps | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
index 9b85a84f6fd4..3fcac789b0a4 100644
--- a/arch/arm64/tools/cpucaps
+++ b/arch/arm64/tools/cpucaps
@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 #
-# Internal CPU capabilities constants, keep this list sorted
+# Internal CPU capabilities constants
 
 ALWAYS_BOOT
 ALWAYS_SYSTEM
-- 
2.55.0.229.g6434b31f56-goog

Re: [PATCH] arm64: cpucaps: Remove stale comment about keeping capabilities sorted

[Fuad Tabba]

On Thu, 23 Jul 2026 at 14:02, Will Deacon <will@kernel.org> wrote:
>
> From: Will Deacon <willdeacon@google.com>
>
> There is no functional requirement to keep the entries in arm64's
> tools/cpucaps file sorted alphabetically and, in fact, they have fallen
> out of order over time. Given that only the arm64 tree touches this file,
> just remove the stale comment and accept that we're collectively not
> very good at the alphabet.
>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Reported-by: Marc Zyngier <maz@kernel.org>
> Signed-off-by: Will Deacon <will@kernel.org>

Reviewed-by: Fuad Tabba <fuad.tabba@linux.dev>

Cheers,
/fuad

> ---
>
> Follow-up from the discussion at:
>
> https://lore.kernel.org/r/20260519092243.7278-1-will@kernel.org
>
>  arch/arm64/tools/cpucaps | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
> index 9b85a84f6fd4..3fcac789b0a4 100644
> --- a/arch/arm64/tools/cpucaps
> +++ b/arch/arm64/tools/cpucaps
> @@ -1,6 +1,6 @@
>  # SPDX-License-Identifier: GPL-2.0
>  #
> -# Internal CPU capabilities constants, keep this list sorted
> +# Internal CPU capabilities constants
>
>  ALWAYS_BOOT
>  ALWAYS_SYSTEM
> --
> 2.55.0.229.g6434b31f56-goog
>
>

Re: [PATCH] arm64: cpucaps: Remove stale comment about keeping capabilities sorted

[Mark Rutland]

On Thu, Jul 23, 2026 at 02:02:32PM +0100, Will Deacon wrote:
> From: Will Deacon <willdeacon@google.com>
> 
> There is no functional requirement to keep the entries in arm64's
> tools/cpucaps file sorted alphabetically and, in fact, they have fallen
> out of order over time. Given that only the arm64 tree touches this file,
> just remove the stale comment and accept that we're collectively not
> very good at the alphabet.

It might be worth mentioning:

(1) The intent of sorting was to make it easier to avoid and/or resolve
    merge conflicts, which hasn't been a big problem in practice.

(2) In the few cases where we do depend on the order of specific
   cpucaps, we've added build-time asserts, e.g. in
   can_use_gic_priorities(), which has:

     /*   
      * ARM64_HAS_GICV3_CPUIF has a lower index, and is a boot CPU
      * feature, so will be detected earlier.
      */
     BUILD_BUG_ON(ARM64_HAS_GIC_PRIO_MASKING <= ARM64_HAS_GICV3_CPUIF);

   ... and we can still do that.

> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Reported-by: Marc Zyngier <maz@kernel.org>
> Signed-off-by: Will Deacon <will@kernel.org>

Regardless of whether you add the above to the commit message:

Acked-by: Mark Rutland <mark.rutland@arm.com>

Mark.

> ---
> 
> Follow-up from the discussion at:
> 
> https://lore.kernel.org/r/20260519092243.7278-1-will@kernel.org
> 
>  arch/arm64/tools/cpucaps | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
> index 9b85a84f6fd4..3fcac789b0a4 100644
> --- a/arch/arm64/tools/cpucaps
> +++ b/arch/arm64/tools/cpucaps
> @@ -1,6 +1,6 @@
>  # SPDX-License-Identifier: GPL-2.0
>  #
> -# Internal CPU capabilities constants, keep this list sorted
> +# Internal CPU capabilities constants
>  
>  ALWAYS_BOOT
>  ALWAYS_SYSTEM
> -- 
> 2.55.0.229.g6434b31f56-goog
> 

Re: [PATCH] arm64: cpucaps: Remove stale comment about keeping capabilities sorted

[Will Deacon]

On Thu, Jul 23, 2026 at 02:13:20PM +0100, Mark Rutland wrote:
> On Thu, Jul 23, 2026 at 02:02:32PM +0100, Will Deacon wrote:
> > From: Will Deacon <willdeacon@google.com>
> > 
> > There is no functional requirement to keep the entries in arm64's
> > tools/cpucaps file sorted alphabetically and, in fact, they have fallen
> > out of order over time. Given that only the arm64 tree touches this file,
> > just remove the stale comment and accept that we're collectively not
> > very good at the alphabet.
> 
> It might be worth mentioning:
> 
> (1) The intent of sorting was to make it easier to avoid and/or resolve
>     merge conflicts, which hasn't been a big problem in practice.

I was trying to get at that when I mentioned that "only the arm64 tree
touches this file", but I'll add some extra wording.

> 
> (2) In the few cases where we do depend on the order of specific
>    cpucaps, we've added build-time asserts, e.g. in
>    can_use_gic_priorities(), which has:
> 
>      /*   
>       * ARM64_HAS_GICV3_CPUIF has a lower index, and is a boot CPU
>       * feature, so will be detected earlier.
>       */
>      BUILD_BUG_ON(ARM64_HAS_GIC_PRIO_MASKING <= ARM64_HAS_GICV3_CPUIF);
> 
>    ... and we can still do that.

I'll mention this too.

> 
> > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > Cc: Mark Rutland <mark.rutland@arm.com>
> > Reported-by: Marc Zyngier <maz@kernel.org>
> > Signed-off-by: Will Deacon <will@kernel.org>
> 
> Regardless of whether you add the above to the commit message:
> 
> Acked-by: Mark Rutland <mark.rutland@arm.com>

Thanks. I'll post a v2 with the author fixed up as well... either my
hard drive or my TPM died this week, so it's been great fun setting up
a new machine whilst in the middle of merging stuff.

Will