From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fanzine2.igalia.com (fanzine2.igalia.com [213.97.179.56]) (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 45827486BBF for ; Wed, 14 Oct 2026 21:44:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.97.179.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792014255; cv=none; b=lUqJRDlGAU1spagbPBdCo2edaZ/PDVrOmc9sZmvi3KGv07EXgAS5jgYqSWxwiOVSLRQYSWOyOLy4ZGcsKWJZEfuo1LJOMGu/IQzME38ass2Vg/+jsG8H6EFSac7FfHDnJew8t99Sz/1ZuoMcCAPK7pvhHFesEn0kfpb+XI0V4Hg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792014255; c=relaxed/simple; bh=2mFZFH/t7Udzmx14+PyJpu/xSr91XvmPAm6UXWNwqGA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=A1Ej6ktfSWu4LEec4943P0TVo4XMXsjDjcFXrPJdpG2wZ9CgFH7HG87XaUsI6j/F5jfbs9c76k2U+lisGfEL7QJircReYAs9U3M0s//ZjNwVW9oKvuQnH0OQvJjoyZ1IWjDuer0YPhHFbwKHpEAFvJRRtf99cdvS1NLCE1MxvEk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com; spf=pass smtp.mailfrom=igalia.com; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b=lbYsagp0; arc=none smtp.client-ip=213.97.179.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=igalia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b="lbYsagp0" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:Content-Type:From:Cc:To:Subject: MIME-Version:Date:Message-ID:From:Reply-To; bh=jdZa5mT6e0C2U/Kjg0oF233p2kgkpg3mIMsYIfiUcPo=; b=lbYsagp04O4Oc3iLW68zu5zMCJ qEMAhGP//WbRVIs1DgvSn+N9NA0nbW1yNxg4f0s5um7pW3Q6GTV6/j9NM8u0KeKp2JQdC/X6F1hWw 9dmQQDhqoQANl78PqeqXAszZjxLSYyiEXFvBM6e5uXadbzKiqRPanSTnX1Xs7IPrJ368jOgA1QvwV hTakF8AbEpnhlAa3dOvhrem3a7SaFyZB7l/A824xWW1H/jU+R3CClP8Hjy7Vm2ikKI5G6hkq9zv3s C2qol7LFHyM5dY7meUAQkQUZS/0M7vsXKoBZo4Fyf98Dv4cw7JF4LZRJzjHUy49V2NwPpHi85pzas aDRfh7ng==; Received: from [177.172.122.211] (helo=[192.168.15.100]) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_128_GCM:128) (Exim) id 1xH6lb-000F5s-IK; Wed, 14 Oct 2026 23:44:07 +0200 Message-ID: <430b10e9-7c8a-44ad-904b-e579250b314a@igalia.com> Date: Wed, 14 Oct 2026 18:44:11 -0300 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v3 1/1] arch: arm64: Implement unaligned atomic emulation To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Catalin Marinas , kernel-dev@igalia.com, Mark Brown , Will Deacon , Ryan Houdek , Mark Rutland , Billy Laws References: <20260930020138.2377090-1-andrealmeid@igalia.com> <20260930020138.2377090-2-andrealmeid@igalia.com> Content-Language: en-US From: =?UTF-8?Q?Andr=C3=A9_Almeida?= In-Reply-To: <20260930020138.2377090-2-andrealmeid@igalia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Em 29/09/2026 23:01, André Almeida escreveu: > Implement support for emulating unaligned atomic operations on arm64. > User applications that wish to enable support for this should use the > pctrl() flag `PR_ARM64_UNALIGN_ATOMIC_EMULATE`. > As discussed at LPC 2026[1], the split lock emulation is probably the first thing that we want to figure from the atomics issues, given that is the trickiest one to emulate correctly given the need serialize two atomic instructions. As suggested by Mark, first we are going to work on an userspace solution that delivers correctness and from there we can better understand what the kernel could provide to help with performance improvements. Thanks! André [1] https://lpc.events/event/20/contributions/2594/