From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 59C9137756B; Fri, 2 Oct 2026 12:22:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790943725; cv=none; b=LlLLWBlpmib1DW6ViUcFTXKb48blXObydqe73Pmy0Zh+PSN7wBBzsMXnrwoHwbhQyuS8Mwa1nGYp9DiZuNJb6yokrrnzeJqYFCl7+XKbjNitFXYX1KYCPWPpc30WWAG47l0u2G+ybG+ZnDIfPDdohN4oKhItgPv3HD7ZPkntinc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790943725; c=relaxed/simple; bh=luMfCZDlUDGUX2+zpExgrzsMoTNW62ItgjO8f4+e7n0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=t+TAhOWRLS6qs2KiOo3M/aqFoAz030pCcL7DEMXUcioOnCF7RSxFHsm/Ss9JvwpxW40SXzsSdfV7Xz1KcYuSoAzOEX2cdvbtwRKsxSX2VuKMv08jJ2SWmYEl1YJ2x7r1/U87sMJK6JkdLciLZZoQfkCe8TIlifCJjwmXMZ89yYo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=T9dhGOCV; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="T9dhGOCV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4B8551F00893; Fri, 2 Oct 2026 12:21:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790943722; bh=Ce2a1myrX+E7TYohZBFJIjnt43b8Lx5Vo9Ht/zpkf40=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=T9dhGOCVQdUIoH7uRpzRsVGY5F49qFVHEBrLBxqHFAGDuAIXoKS1xhlo9AHRPemjl JRk6CHalHqos1q8v+ayc59QPqujmTYHK7JTUvE/BscPv4v+7psZocfv7PUyBkJA+qx 9Og9uFdzJPDh3aFL/5/0E2nXCZfiP+39kMF1YHtHFb6x9sLpsiNZalCl+TLegXyBij 6Ztord/uSDPf+I+yczyV9L2Jdg+/70XWz7dPoDn/FYJvGioJQ0fNoh/j3x0xS92tJe y7rGK+iQFw8TvsNJDUYORs2W3V2P+QYCF4AG0AdWtUQD2Q6qhzcr6CGA37M3DTGvrm iLTs4uxEsY/cA== Message-ID: Date: Fri, 2 Oct 2026 14:21:53 +0200 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 1/2] selftests: run tests on nommu architecture To: "Lorenzo Stoakes (ARM)" , Geert Uytterhoeven Cc: Hajime Tazaki , johannes@sipsolutions.net, linux-mm@kvack.org, liam@infradead.org, rbm@suse.com, akpm@linux-foundation.org, luto@amacapital.net, brendan.jackman@linux.dev, liuhangbin@gmail.com, corbet@lwn.net, kees@kernel.org, broonie@kernel.org, mhocko@suse.com, rppt@kernel.org, shuah@kernel.org, surenb@google.com, vbabka@kernel.org, wad@chromium.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-um@lists.infradead.org, daniel@thingy.jp References: <20260929235711.2287931-1-thehajime@gmail.com> <20260929235711.2287931-2-thehajime@gmail.com> <94759bed23f00d2044005e36be6f72f297e092f0.camel@sipsolutions.net> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/2/26 13:53, Lorenzo Stoakes (ARM) wrote: > On Fri, Oct 02, 2026 at 01:38:31PM +0200, Geert Uytterhoeven wrote: > >> On Fri, 2 Oct 2026 at 10:10, Lorenzo Stoakes (ARM) wrote: > >>> But fork() -> -EINVAL or -ENOSYS = nommu, then just have the child quit and >>> etc. should do it. >> >> fork() is not strictly an MMU-feature (you can implement fork on nommu >> if all memory accesses are done relative to a base address register), >> while I think mprotect() is an MMU-feature. Unless it can also be used >> to change the protection using the one or two BARs most MCU haves? >> Anything else that is a real MMU-feature? Non-identity mmap()? > > Does any nommu arch implement fork() in linux? I was about to say, that sounds a bit too theoretical for me. IIUC that is not implemented, and if someone would propose it we would likely just nak it. In the unlikely event that this would see the light of day, we could always change our detection in the selftests. -- Cheers, David