From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id E288BC3DA4A for ; Fri, 26 Jul 2024 17:39:40 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 55ADA6B008C; Fri, 26 Jul 2024 13:39:40 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4E4236B0092; Fri, 26 Jul 2024 13:39:40 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 384CA6B0093; Fri, 26 Jul 2024 13:39:40 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 18C0D6B008C for ; Fri, 26 Jul 2024 13:39:40 -0400 (EDT) Received: from smtpin23.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 90DB1C19F6 for ; Fri, 26 Jul 2024 17:39:39 +0000 (UTC) X-FDA: 82382616078.23.B0E689A Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf12.hostedemail.com (Postfix) with ESMTP id C98B540023 for ; Fri, 26 Jul 2024 17:39:36 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b="DV/Z7vEt"; spf=pass (imf12.hostedemail.com: domain of broonie@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=broonie@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1722015552; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=KghTAcymQ39wqpYk50EVm2j8OidEx8e/OH8Z/Q3m4Ns=; b=EVy8sgskBt1Q5YdMzerHj+TRdr8dsEGnZSRbI76zDXNpsikltIVwocdR04FYhmU0seBK5k Bd1Y/8s7z/d9nEO6b7v/rYnYjI8GV1LvN1EXyB2ZKKVrxGHUFSfTnnCC1BCKcWx2bzGlEL VZWMYvKyrl/WmwQ4ohaCo2yyeuw+1Gw= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b="DV/Z7vEt"; spf=pass (imf12.hostedemail.com: domain of broonie@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=broonie@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1722015552; a=rsa-sha256; cv=none; b=XnKCr4ErWKBZOmmGmxu28rvwjpBwMapg67pgDcEOBHKumftC8UP0Q5abPRh9kPBpgIjfCo vqo/zTbuB+Wx/+5V+3H+1zHtq6ubYSZbwp41bW05CatHHsIyZA1I+bz8kxizKieBrq0rjX c9CtkdgOUuARcEH7msEhV0cyhqaMvrQ= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 865E86181E; Fri, 26 Jul 2024 17:39:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 184F0C32782; Fri, 26 Jul 2024 17:39:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1722015575; bh=8w1mM4hsz30RIDmoijcUZjPnnrqcKXvR4sSqM1tep/4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=DV/Z7vEtOQ6fpK1XlwOsYQ7qcHj5loTqEE6QOhCsSqjvyq9NRvKlcmNtdC2g8jhY6 aWv73Vf0gzmua1r6eBaKdypdddT45gnW/E0ABD3it7eli5FXDS+vnvrvDj+V5Zfuuf xJNXr3X9g2ZxiiKEMQrknbNds0YasB4VTugZ9IQSP4WKpt7pUqp9dLjKWUReroNOBk zdaLXSY7z39Eb+B855w+mW2obCbZIuBQWm6KGs+ypfSLztcWYns4CkQV6YGLM+lL6w dPuiR8OQU9eJqPpaihNfj/a0aVBCnjAMFu+cCYtlW4GgQA0xW00IYT91LmXOdgA9e2 EkBh389uPh7Pg== Date: Fri, 26 Jul 2024 18:39:27 +0100 From: Mark Brown To: Dave Martin Cc: Amit Daniel Kachhap , Joey Gouly , linux-arm-kernel@lists.infradead.org, akpm@linux-foundation.org, aneesh.kumar@kernel.org, aneesh.kumar@linux.ibm.com, bp@alien8.de, catalin.marinas@arm.com, christophe.leroy@csgroup.eu, dave.hansen@linux.intel.com, hpa@zytor.com, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, maz@kernel.org, mingo@redhat.com, mpe@ellerman.id.au, naveen.n.rao@linux.ibm.com, npiggin@gmail.com, oliver.upton@linux.dev, shuah@kernel.org, szabolcs.nagy@arm.com, tglx@linutronix.de, will@kernel.org, x86@kernel.org, kvmarm@lists.linux.dev Subject: Re: [PATCH v4 18/29] arm64: add POE signal support Message-ID: References: <20240503130147.1154804-1-joey.gouly@arm.com> <20240503130147.1154804-19-joey.gouly@arm.com> <229bd367-466e-4bf9-9627-24d2d0821ff4@arm.com> <7789da64-34e2-49db-b203-84b80e5831d5@sirena.org.uk> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="jKu8x7uvwJS8RqOX" Content-Disposition: inline In-Reply-To: X-Cookie: It is your destiny. X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: C98B540023 X-Stat-Signature: iumpntj6ff6xyeo3jx6dwisqisxu4quy X-HE-Tag: 1722015576-831777 X-HE-Meta: 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 b16fMORL Gci4RPO0LjszW6dp7+4B4//wdHZvWW1SiEat/vPDKKiimhjkS2ZOxJV+nUNiJ3dsA7J5TC2IHzoS9PnB92/uwJKIRJp61KwRSwE+zJb2A2w2H7WgQFKAGoVkfQCLi1rtdqba73rI8L0O59uCoZONWQdq1OGvqudYgR15Emo85cjeAYAEIxitZe41oHegjX0RQC+hLDs/VN2FW+bF2x0ZZwWMRnA2o7LwAou/KVHC7DqodkWNUxnG9l5kwz1l/QtTKrfLj7pYby+kpOa6nWsNd4Xa0vH//eF18o7OL X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: --jKu8x7uvwJS8RqOX Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Fri, Jul 26, 2024 at 05:14:01PM +0100, Dave Martin wrote: > On Thu, Jul 25, 2024 at 07:11:41PM +0100, Mark Brown wrote: > > That'd have to be a variably sized structure with pairs of sysreg > > ID/value items in it I think which would be a bit of a pain to implement > > but doable. The per-record header is 64 bits, we'd get maximal saving > > by allocating a byte for the IDs. > Or possibly the regs could be identified positionally, avoiding the > need for IDs. Space would be at a premium, and we would have to think > carefully about what should and should not be allowed in there. Yes, though that would mean if we had to generate any register in there we'd always have to generate at least as many entries as whatever number it got assigned which depending on how much optionality ends up getting used might be unfortunate. > > It would be very unfortunate timing to start gating things on such a > > change though (I'm particularly worried about GCS here, at this point > > the kernel changes are blocking the entire ecosystem). > For GCS, I wonder whether it should be made a strictly opt-in feature: > i.e., if you use it then you must tolerate large sigframes, and if it > is turned off then its state is neither dumped nor restored. Since GCS > requires an explict prctl to turn it on, the mechanism seems partly > there already in your series. Yeah, that's what the current code does actually. In any case it's not just a single register - there's also the GCS mode in there. --jKu8x7uvwJS8RqOX Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmaj304ACgkQJNaLcl1U h9CeVAf/WJj2W/iYeqVHnIEx+p4FWw5ApJBNcEdmXOIBDVGUJEIji/s5+DIMmTsR GnMMoGn0PGovhD7ABJPly+Ysr1Ma/cWGs/eia+AhmGLvDh7ATNWxUWPWoQpfH4vI FFXbia4AkmLZ34lsI6P1BKT5wTRVWQj9QaTTCFxVdoNmBF7nYgnT0u0A4Od9O9Vm iX064HfEvrM/PwRID8FMKY2pXuOWTRWJrQ7X1l75V7H0wdUW1h6b5tWIyUuoZIOl RChlS70kcpLdwt6Y0KjNj5bblDCwZ3KNQPEVcEWq2lMChKzoxm1I1QNmc7XEAqf9 JC4bAZwKKaKlseDDs61j4qyz/Nj1Hg== =DfYC -----END PGP SIGNATURE----- --jKu8x7uvwJS8RqOX--