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[93.36.100.117]) by smtp.gmail.com with ESMTPSA id 16sm2813615wmi.0.2020.02.06.00.29.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 06 Feb 2020 00:29:08 -0800 (PST) Subject: Re: VW ELF loader To: David Gibson References: <20200203012842.GD52446@umbus.fritz.box> <8420784f-b4c7-9864-8534-b94dbc5f74ff@redhat.com> <20200205055851.GH60221@umbus.fritz.box> From: Paolo Bonzini Message-ID: <73105e0b-c0a0-009f-aeba-fec818d3088c@redhat.com> Date: Thu, 6 Feb 2020 09:29:07 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 MIME-Version: 1.0 In-Reply-To: <20200205055851.GH60221@umbus.fritz.box> Content-Language: en-US X-MC-Unique: N_1KNeP8MgGwprb4UyOY_A-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.120 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Thomas Huth , Alexey Kardashevskiy , "qemu-devel@nongnu.org" , Cornelia Huck , Christian Borntraeger , Stefano Garzarella Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 05/02/20 06:58, David Gibson wrote: >> Yes, SLOF is big and slow. petitboot is not petit at all either, and >> has the disadvantage that you have to find a way to run GRUB afterwards. > Well, not usually. Petitboot parses grub configuration itself, which > means that generally from the OS / installer point of view it looks > like grub, even though it's not from the actual bootstrapping point of > view. Ok, sorry about that. I need to learn a bit more. >> But would a similarly minimal OF implementation (no network, almost no >> interpret so no Forth, device tree built entirely in the host, etc.) be >> just as big and slow? > > So, as actual OF implementations go, SLOF is already pretty minimal > (hence "Slim Line Open Firmware"). If there's no Forth, it's really > not OF any more, just something mimicing some of OF's interfaces. Right, not unlike what you get with vof=on. :) I'm not against at all that idea. I just don't understand what you refer to below as (2). Does petitboot not have the problem because it kexecs the new kernel? Paolo > But the difficulty of SLOF isn't really its bigness or slowness in any > case (the slowness is just an additional irritation). The two big > issues are 1) that it's written in an obscure language and 2) > synchronizing its state with things that require host side > involvement. > > Rewriting a minimal guest side not-OF would partly address (1) (but > there's still the logistical pain of having to build and insert it), > and wouldn't address (2) at all.