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 098303F7A8A; Mon, 29 Jun 2026 08:41:56 +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=1782722518; cv=none; b=pGlCTg8MOSfJxpZ9QgbC0MRnM6O8hy/ARCpCeAkcYK5v8mfeT07iOW5u6BkrqcglKj58VqEfawqhgBLfI+WQHxs7UsB1Qx6FH+uUiyOPN3NEErHTIbGK32SZzYADnITdw4sTGe7ws19D/4ZNRE8Z8lDIyjRjLD0kcYHT/ba1wIA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782722518; c=relaxed/simple; bh=7bXhaRyT/bphOsfXW9GyN/IlPMW3EPmBRgUqb5OUh2E=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ahzt2fhhgkmf6xo4N3caAAlSn2z+hMjI7nFjeYH2zVyE9op+3WQ8lQPiZwBO+aA6FCtajsJsk+PPXXT1TSAxRn72zUf7XgEnTeDuq8Ivfr0uK/zKcwJ6htINjvbzT+EWLvW1HuvRPUDPAbg2P7HAxBxc/d3tJZXZ8SXByViHuJw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=V5zQHqd4; 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="V5zQHqd4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6D2E31F000E9; Mon, 29 Jun 2026 08:41:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782722516; bh=H/zDbGIgXBHN1TlkRmk8Byzr+c6I/SPigBLVgROiABE=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=V5zQHqd49XcnPm1RyK0Bl8kqIUsykC7jBrFLM2r5GflAQ9E/nRBLatEThzTKX6s8G 06vJXogElrHlxQ2glcxCcbUbQ3qFad+kmIAKS3f/5CkNl16MfrZlq/qtNSNiwT5nXM ymbrxfUdjBaKFG1aIi4RudzvfkfTmRbSsRoWDWGozhlbYBIpE/95GXTkt7H8sf0dOj irznKQCCOjf9GkCGX2YcmOnDHo3kqBPkUNEwfCvS7N+ynyVNhnDbm0eosXhDNuB+9X IwvXHhc8cYHKrhVbzP/j3HpSoUHe5vLVHEsYRS/cFFjfFlNKKI3yGau6d5PVc/uROR 1B5oLteWGQ8LA== Message-ID: <00d29422-b887-41cc-a41d-a6177bdd2edd@kernel.org> Date: Mon, 29 Jun 2026 09:41:52 +0100 Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC 00/12] RFC: Devicetree-ACPI hybrid mode To: Bjorn Andersson Cc: Hans de Goede , "Rafael J . Wysocki" , Konrad Dybcio , Srinivas Kandagatla , Krzysztof Kozlowski , Dmitry Baryshkov , Bartosz Golaszewski , Abel Vesa , linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, linux-acpi@vger.kernel.org References: <20260623145225.143218-1-johannes.goede@oss.qualcomm.com> <04b4f1b0-4d8f-41eb-9b6f-d90b88aec2ff@kernel.org> From: Bryan O'Donoghue Content-Language: en-US Autocrypt: addr=bod@kernel.org; keydata= xsFNBGRJNSgBEADD7Vm2ZFa+v+JGJ2QYTJqQAkqis/uOHkhdFNXqpBarVBd47QU/DMNU5Rxg jedMQEmHoeDbJ6UOpjbrUQ63c5sgG1JbroHJJctwsEI75OOlekMuebEbjIJBLfgENGwPBMHv piv5TgCWr0VgYaXfp2eh2LINFywzqj823HiDPibQAXDrjzvF1ogksi/6cQZs8d4if8YQkLOr YISFouG+eR0nN1I7mUfIddXOWu6lJeTyqbWVurv58k2ekIXKaOC9ixLHFbcfYV0hOgRaTwQC B8CYF9nfqZla19iItfsN9QxN+ZdQjcRoYipp6HPCMfJlKH7GfaFcW93LKc4DKJ2lVL+pg/OQ lythZbjRPY492NG9kZ65aYstCs90uhMUEVVPuGUw7wBEku+6IEwZfrbMVKeWzLlPyM4Hv9hM 8ktxSmxWsPTPqpBC8eyeAQLalMELAyVcZlkaCtEcbj7w4l/JkYz+4l37obG8ZD+B34udBUUz MsAJ8foDFrBh2MOFA3hxD6G90D23mmWsri7pnKA2tZs92aQX7Ee+FbCyg6g5ln62Sq83ZDbf 53DdBs55EVpBadeInWmXhzCHPQx06H+CwTEjShTYIaMmBfrewvYUDKvFTC5iKQhAEUgt6i94 JsbG7NoeqcxkUMcBOEUQ3uCQG1D70ugspgXc0wd3Rimiq6535wARAQABzSFCcnlhbiBPJ0Rv bm9naHVlIDxib2RAa2VybmVsLm9yZz7CwZEEEwEIADsWIQTmk/sqq6Nt4Rerb7QicTuzoY3I OgUCZ+R+mwIbAwULCQgHAgIiAgYVCgkICwIEFgIDAQIeBwIXgAAKCRAicTuzoY3IOimUD/94 BwVEJX31JRe2sxbB/e1w2p8x1bxvTw5AeIzpV3ox7coJg1bSU2mnGuj1V4o0Yxf/3zmcJzCN VfVjwRF8Ii3GnC7uUXk2t+87piQfKTyJAYQABhZUKgoVJbjJq/S+C3XCKIyBA+EiezoUsgsA jTzwU+FzV7zVWIXFPJNtBERLwboE9w9U3KjAExOa1kSY8eLrsg6kOwlOHWy5UsQqYOjrS96M mzm2xuc1+RCjrndAyYhCnrOKvJ67HsPnBeJCjw7ImGD/U1GchwYbX8o3DO3JNHm3qfC86ZqX 2sCouENg4OzgPTtLKUrueM6xsu6KMM7gj17vxsiR3KQEoJnnMB8D1xtBofN3mFZE0wD9M24m 8yGunZbtntMCUHzIrlJgAPwKWKuGOYtA8UgMTFkccnUJtQrg9KotKtEF/FuftG9zLG9XEkt4 5ZdNgbSoLWgelu3T47mbOJ8LHhiLaCWP7yrovtVAvLUQ1BsiA42u8ECrFCFvQj9nrejE/ICv kP+uqcKtdDvP9HrIGycF1WZyfZLp0RvopKW92FLvI4I1QFWJ+wenk6+LGyJ5bzlrWzevjxmf nHcXE6sJBHrE7eijlbbImDAi3uLYN8Nd9Dm11IDAy4GAIQxSiQn0yblDhPiyGtchy80EVkCm g9k17Wol+2E2mC4DKgVdCkyUtTRSLgsJCs7BTQRkSTUoARAAuTnmWHBS6izRcEE93ajpzI7h dgQO4U3IRvOEsvIKR5NGcNEs0ngGebwsZ/lVULjN4vYU0LleqVhPBidNXUoZCN3A0F0Z2Ov8 NZdef+2EhQPBVWxFO7JBzhe8Z3ALj+wFtlg8akJjBzU56azW/iJzAobqHVrudzKoO2b1/CMg VbiAQ+RXjgfN5kY/HqYDU7mw+hXuUV9PbtX1L8xqQQac95oM9rHzKHHpiVwxTeJnGQsa+THi Kze+YET3rCoGHMvOQEJhdrucTv5FpAakKdkOFNel9FFckLRKEuWgCzhpFsjQ7xbirQgFUxG9 vlk1+q4hMRGNyEqoD6svYEeqbiUSd0oPUJeioiC3rNMRCNHLVrfZ2J6SCPkxfda08uzSdDQU 1/YPjOh8ZtQDMu7WctZ3XO288Z1gyBR49V7fbFs2w4sQxG+h/enlxqP7fdw1mjUlZjU5huCJ ielS0oEaIpmUpkugli7x4WhwLnhK2EbSoz7nLBC0y+ALUOdMlz/Y1l9xRt+bkDhpmf4O4IcI MxgZ0QMLq8rHDkGaEbsgZZHQPS58T0XE3IP30Q9SNxsruCMXtd2hYtBssf/wohc6JVsTtMg2 VYTPDPIFNZFSXupEJB7jlqpDWJ8ooJfJRLBatbjT5+mVQaMYB7Hs/t+zWYWaJKHyc8O6WLEC NUV5Tdt5EkkAEQEAAcLBdgQYAQoAIBYhBOaT+yqro23hF6tvtCJxO7Ohjcg6BQJkSTUoAhsM AAoJECJxO7Ohjcg6LuIQALnXt36OUuK43wqw6UYt0cnN6EbUqJHApAF5eNFn0jCCB2XELjSz JKJwuNAweowBdabiBniJ+501WIW+ewEsz1uby5fUQjZuCEsIkuaIluyfUFPb73qrQyAGuusd 7teA4WT+/jUku9g7lX5sVoRCrKQPkd16f6Bzfztyqyjcn43/X5yQI+wlboQ6HuKe/3I3yiOx OgmCHzOawpC9PvhEcKj79RLM3Zz5Ts5AuHpRX70Jz8Be76LwVFLp5Msx3S24ZTU1lBo2uiJ3 xSkay2lTpyVWRPx9vgcwzxGguOPJQJwsQeLb7wpoJMPpD3ERoaRii7Q7hvmxklpZjhKYWB3d t6nQ497Ek9loCrp3MIjRCSDN5xEGffiHks9yTeGMUQwO4tX8RE04uOJPkUY7uCFzFqN6/qey X3oFfPgkULMdiHofPAL1OskZSTzGPSfTYRE46NCJw8yoZBQ/oOyWeqaUQbK0wmW/g81wm8p7 LKSGEglMpiX07M1AotgvylN5C8fjbouoK+/RAMsXkk8jba6rPfuuXPaDjCyyKn6zSVHETnHW 3AJbgVY50T8STpnxayBQvWbCvu+6NOEjXCbyaOJig+5l0zlGN9XHjdANXC5HnwmyaGRL9YDq Jh2nVXVJDincOdQRdKcJjYLqaOAoWrYWSDi1iZGspHBTDrnOvfMQzzHY In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 29/06/2026 02:34, Bjorn Andersson wrote: > On Fri, Jun 26, 2026 at 03:43:59PM +0100, Bryan O'Donoghue wrote: >> On 26/06/2026 15:33, Bryan O'Donoghue wrote: >>> On 23/06/2026 15:52, Hans de Goede wrote: >>>> Comments, thoughts ? >>> >>> Throw out DT and just do this... >>> >>> One thing I like about this approach TBH is that you don't do the easy >>> thing of presuming to push the hard work into the bootloader - thus >>> creating a dependency on bootloader. >>> >>> We've had _alot_ of problems doing DT selectivity to get OSes installed >>> on arm64 laptops. You mentioned I2C-HID devices and EC controllers which >>> I agree are a good and obvious targets. >>> >>> I don't think this can replace a full and complete DT but, then I don't >>> think that should be the objective. >>> >>> Much like installing cursed OSes like Windows on "normal" laptops or x86 >>> machines, you'd expect to boot in ACPI mode have enough of the OS >>> running to install more of the OS - which I think _can_ be a viable >>> objective with an ACPI-DT translator. >>> >>> Sadly OpenBSD could boot all the way to console on the Qcom laptops >>> where Linux could not - because ACPI support was better there. >>> >>> And, we have Nvidia laptops coming too, Windows laptops which will parse >>> ACPI tables to boot. >>> >>> There's almost no upside in having ACPI data and not trying to make >>> maximal use of it, especially if you don't have a DT supplied by >>> antecedent boot stages. >>> >>> --- >>> bod >>> >> >> I'm going to agree with myself some more on the boot story. >> > > Good for you. >> As a Linux user I don't expect everything to work, especially so on aarch64 >> but, if I can get to a boot console with a screen and keyboard - I have >> scope to play in a way I otherwise don't - parsing DSDT from Windows and >> walking backwards to DT. >> > > We supported this on SDM850 and 8cx, we had sufficient amount of > support/quirks in Linux to allow you to boot and run the Debian > installer - but that's how far it was possible to push things without > improving ACPI specification and tables. > > Given that you couldn't run any real use cases, this was not adequately > maintained and as we moved on to 8cx Gen3 I argued that we should > prioritize the DT-effort. Boot to console is infinitely superior to not booting at all, if OpenBSD can boot to console on day 1, a community project with no funded effort, how much effort is really involved in Linux being able to do the same thing ? https://undeadly.org/cgi?action=article;sid=20240620105457#:~:text=se%3E%20Date%3A%202024%2D06,I%20beat%20my%20last%20record. Console, keyboard, NVME, USB. I believe their policy is also ACPI to bootstrap until DT gets going sufficient. There's nothing to stop populating DT nodes with ACPI data being part of that boot story. >> DT _should_ be the landing zone of course but, ACPI-DT hybrid to "just boot" >> seems like an obvious yes to me. >> > > But this proposal doesn't give you ACPI+DT, it gives you DT+ACPI, you > still need a base DT that is somewhat functional - and then you > explicitly need to make references to the external ACPI representation. > > Quite nice for experimentation, but I don't think it will solve either > of your problems. There are two arguments, three really. - Boot in ACPI mode to console. This should be done, it at least allows people to tinker with their hardware. - DT-ACPI mode. This proposal. Surely worthwhile doing and not incompatible with your notion of shipping an upstream compliant DT somewhere. In fact it might even let you boot enough of a system based on a silicon vendor DT that never changes to again - allow end users to actually do something with their hardware absent lots of upstream churn post release. - ACPI-DT mode. It is entirely possible to have Linux eat ACPI tables and produce in-memory DT. Not easy or nice but technically feasible. It could even be hybrid with the first bullet point. Either way supporting more ACPI on the boot path shouldn't be a barrier to better DT support. --- bod