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From: Joey Gouly <joey.gouly@arm.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: Mark Brown <broonie@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: kernel-hwcap.h change causing full kernel rebuilds
Date: Tue, 21 Apr 2026 13:56:28 +0100	[thread overview]
Message-ID: <20260421125628.GA3849283@e124191.cambridge.arm.com> (raw)
In-Reply-To: <52fb2e8f-3e1c-4cf5-a02a-0d68beedd18b@kernel.dk>

Hi!

On Tue, Apr 21, 2026 at 06:52:55AM -0600, Jens Axboe wrote:
> Hi,
> 
> Maybe this has already been reported, but a quick search on lore did
> not find anything. So here goes... After commit:

Here you go!

https://lore.kernel.org/linux-arm-kernel/20260413-arm64-hwcap-gen-fix-v1-1-26c56aed6908@kernel.org/

and on it's in rc1 now:

https://lore.kernel.org/linux-arm-kernel/aeaDFH0-2zhOQTxy@arm.com/


Thanks,
Joey

> 
> commit abed23c3c44f565dc812563ac015be70dd61e97b
> Author: Mark Brown <broonie@kernel.org>
> Date:   Mon Mar 2 22:53:16 2026 +0000
> 
>     arm64/hwcap: Generate the KERNEL_HWCAP_ definitions for the hwcaps
> 
> arch/arm64/include/generated/asm/kernel-hwcap.h is generated for
> _every build_, which means that you can literally run make back to back
> without _any_ source changes and you are rewarded with a full kernel
> rebuild. Not sure how this ever got past any kind of testing, because
> it's very noticeable.
> 
> For now I've reverted this change locally as any kind of testing now
> kicks off a full build, when a single file rebuild is all that is
> needed.
> 
> -- 
> Jens Axboe
> 
> 
> 


  reply	other threads:[~2026-04-21 12:56 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-04-21 12:52 kernel-hwcap.h change causing full kernel rebuilds Jens Axboe
2026-04-21 12:56 ` Joey Gouly [this message]
2026-04-21 13:00   ` Jens Axboe

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