From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1B77D15098A; Thu, 12 Sep 2024 17:29:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726162183; cv=none; b=g5EOigVpMQ5ZMXxSSf2vYXpgX3PWY94J7A2RQcoJIpiLI42DeSJ2uO3C/FhVLhceNSsnt+dONnp7fjT869wqc2Zli2omZI4gPxXVqNqwEJ2SpSyqR4OHr13TVqW+KxvFUyar5U7dxI/Y/dek60jr4F60IwYWEi1/JzWHMBLRuY0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726162183; c=relaxed/simple; bh=zDGznEn/StT0eacvGsbWQqOmyRaA1BKWZvptYgykthA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=d/CjdEvpaoHtPaJK3+4k+UkCSgMRjQ9PpW2ZvvF2makzVvcUsTSTk5bPuDahY1MFiXvixrrHpOcYA+jFL9MghhRHt+wQYwRu87AGWZgRF+jqE8mySDJJL49F7nLIpb/LcCOfx5VuKGG8zNWDnXLq1CXnLe1YQUJlDE2qM+i4HfQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ILfeSbw+; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ILfeSbw+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E57E1C4CEC3; Thu, 12 Sep 2024 17:29:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1726162182; bh=zDGznEn/StT0eacvGsbWQqOmyRaA1BKWZvptYgykthA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ILfeSbw+ykMKzupv4qU1xlaCnMmDg80aCV9c/GQ8X1ITGrUufUpoEUhKQivsfZt96 mIl2oZmkrvZ8EQ78pc7uNOHIm2BHJEl+ct8or6iRF1Gsy17jWW0Cdgr2jtscW7rc8P rn8JQLaFDgCjckH1eN92sIqA8UTxyEFoDIfo3BWyeEUrDTeRjrhH+lVTXxh3G1X/1L 3EWncvTiw65P6HteNwzHx3AKz6C5wisCIQs57AEBEVwm+C+/wf/VeDNv36l70XU53a AZFcv3AOQwH4qSGsx1LsWQBYsjOfJvlFEF0tYqxK9B7C6sXnovn8nwb0YZxrguOuQd rFc0ZuLmvSknw== Date: Thu, 12 Sep 2024 18:29:36 +0100 From: Mark Brown To: Catalin Marinas Cc: Alexander Viro , Christian Brauner , Jan Kara , Eric Biederman , Kees Cook , Will Deacon , Jonathan Corbet , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Yury Khrustalev , Wilco Dijkstra , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org Subject: Re: [PATCH RFC 0/2] arm64: Add infrastructure for use of AT_HWCAP3 Message-ID: References: <20240906-arm64-elf-hwcap3-v1-0-8df1a5e63508@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="PY2TG83/gvDfQre4" Content-Disposition: inline In-Reply-To: X-Cookie: Happiness is the greatest good. --PY2TG83/gvDfQre4 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Thu, Sep 12, 2024 at 05:45:45PM +0100, Catalin Marinas wrote: > On Fri, Sep 06, 2024 at 12:05:23AM +0100, Mark Brown wrote: > > We will at some point need to bite this bullet but we need to decide if > > it's now or later. Given that we used the high bits of AT_HWCAP2 first > > and AT_HWCAP3 is already defined it feels like that might be people's > > preference, in order to minimise churn in serieses adding new HWCAPs > > it'd be good to get consensus if that's the case or not. > Since the arm64 ABI documents that only bits 62 and 63 from AT_HWCAP are > reserved for glibc, I think we should start using the remaining 30 bits > of AT_HWCAP first before going for AT_HWCAP3. I'm sure we'll go through > them quickly enough, so these two patches will have to be merged at some > point. That does seem like the easiest path for everyone, assuming that there hasn't been any usage of the remaining spare bits we weren't aware of. > We'll need an Ack from the (arm64) glibc people on the GCS patch series > if we are going for bits 32+ in AT_HWCAP. Yup, hopefully Yuri or Wilco can confirm prior to reposting. It does seem like it'd be good for glibc to add whatever support is needed for HWCAP3/4 now anyway so that whenever we do burn through the remaining bits on AT_HWCAP there's less friction as we start using them. --PY2TG83/gvDfQre4 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmbjJP8ACgkQJNaLcl1U h9A5uAf/dRvyo0ETJshkqYxCUdY9OOrC8VAw6izGokC7Pbig9GfOGMbwramzsIPK 79bkWe8NRIYB/ZAPmQJE5on/o7LIfGKmBacSz/hRBUzB0frm2utsQSbFzxOlUZdw gBfOhfJ0WT9Fr2HWojcoHFy3Wrlh7yU6fCxLptsclItcYQ66OHqPLyZ3ZmhMJfke CdE0ibgG4E5bMwpDHwmUFct9PkaIxLm8G80VBU3h8584BCTGEgy+0zGPfQBi8CBF f5SeikY/4ZtCA+SznibclKPw5u0Ow7Z5jmP6/CPInfu0a71R8/nkmAiLJ0hBr7IO NsADawEmyVdwQRMhsRpMwtW/HNdULA== =ra9H -----END PGP SIGNATURE----- --PY2TG83/gvDfQre4--