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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2A2FBCD5BDC for ; Tue, 19 Sep 2023 15:22:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233125AbjISPWU (ORCPT ); Tue, 19 Sep 2023 11:22:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46098 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232679AbjISPWP (ORCPT ); Tue, 19 Sep 2023 11:22:15 -0400 Received: from www.kot-begemot.co.uk (ns1.kot-begemot.co.uk [217.160.28.25]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E005BE5; Tue, 19 Sep 2023 08:22:09 -0700 (PDT) Received: from [192.168.17.6] (helo=jain.kot-begemot.co.uk) by www.kot-begemot.co.uk with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1qicXc-002SL8-Lu; Tue, 19 Sep 2023 15:21:32 +0000 Received: from jain.kot-begemot.co.uk ([192.168.3.3]) by jain.kot-begemot.co.uk with esmtp (Exim 4.94.2) (envelope-from ) id 1qicXZ-00Ft9g-WC; Tue, 19 Sep 2023 16:21:32 +0100 Message-ID: <9a5c0856-d542-9912-7494-53d7fe4538a3@cambridgegreys.com> Date: Tue, 19 Sep 2023 16:21:29 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: Arches that don't support PREEMPT Content-Language: en-US To: Thomas Gleixner , Peter Zijlstra , John Paul Adrian Glaubitz Cc: Matthew Wilcox , Linus Torvalds , Ankur Arora , linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org, akpm@linux-foundation.org, luto@kernel.org, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, mgorman@suse.de, rostedt@goodmis.org, jon.grimm@amd.com, bharata@amd.com, raghavendra.kt@amd.com, boris.ostrovsky@oracle.com, konrad.wilk@oracle.com, jgross@suse.com, andrew.cooper3@citrix.com, Geert Uytterhoeven , linux-m68k@lists.linux-m68k.org, Richard Weinberger , Johannes Berg , linux-um@lists.infradead.org, Brian Cain , linux-hexagon@vger.kernel.org, Richard Henderson , Ivan Kokshaysky , Matt Turner , linux-alpha@vger.kernel.org References: <87zg1u1h5t.fsf@oracle.com> <20230911150410.GC9098@noisy.programming.kicks-ass.net> <87h6o01w1a.fsf@oracle.com> <20230912082606.GB35261@noisy.programming.kicks-ass.net> <87cyyfxd4k.ffs@tglx> <87led2wdj0.ffs@tglx> <0e69f7df80dc5878071deb0d80938138d19de1d1.camel@physik.fu-berlin.de> <20230919134218.GA39281@noisy.programming.kicks-ass.net> <87y1h2ur98.ffs@tglx> From: Anton Ivanov In-Reply-To: <87y1h2ur98.ffs@tglx> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Clacks-Overhead: GNU Terry Pratchett Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 19/09/2023 16:17, Thomas Gleixner wrote: > On Tue, Sep 19 2023 at 15:21, Anton Ivanov wrote: >> On 19/09/2023 14:42, Peter Zijlstra wrote: >>> If you're working on one of them, then surely it's a simple matter of >>> working on adding CONFIG_PREEMPT support :-) >> In the case of UML adding preempt will be quite difficult. I looked at >> this a few years back. > What's so difficult about it? It's been a while. I remember that I dropped it at the time, but do not remember the full details. There was some stuff related to FP state and a few other issues I ran into while rewriting the interrupt controller. Some of it may be resolved by now as we are using host cpu flags, etc. I can give it another go :) > > Thanks, > > tglx > -- Anton R. Ivanov Cambridgegreys Limited. Registered in England. Company Number 10273661 https://www.cambridgegreys.com/