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 X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C6571C433DB for ; Tue, 9 Mar 2021 10:21:12 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5B2B965267 for ; Tue, 9 Mar 2021 10:21:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5B2B965267 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:35946 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lJZUF-0005vt-D7 for qemu-devel@archiver.kernel.org; Tue, 09 Mar 2021 05:21:11 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:46596) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lJZTX-0005PV-Fw for qemu-devel@nongnu.org; Tue, 09 Mar 2021 05:20:27 -0500 Received: from mail-ej1-x62e.google.com ([2a00:1450:4864:20::62e]:37832) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1lJZTV-00018z-KX for qemu-devel@nongnu.org; Tue, 09 Mar 2021 05:20:27 -0500 Received: by mail-ej1-x62e.google.com with SMTP id bm21so26295251ejb.4 for ; Tue, 09 Mar 2021 02:20:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=mU5fOuFa0asJ8/RqiN8lVAPTh0kpPR9/MXoDY9LeyHk=; b=hmR0Emnukv3Qle3tac0EDMCsbPtDvOVCu3BruGWDk6FOKH51aAO1rfMs+8r4xhxXgC 9etHA7WXjz2PGzyaIaD30qUTul0WJ+v5liU9Lhep+tlFaDMs7vcIHE01wlAHJjp1pLb0 HjAACEWXpF76e9ZRR8UwxwSPInEMb6vZe/yDWMSiCUd8Wr0Hot0myV5YMJh7fqrEY+mX 0J4znxigulqCGHLh5VTOUDrGcwusVx4f7TZxIEvuMxPnjiFIua5Bf9RXasRolg+tJ/h5 7nxN4lqUHf7TOwNG0dKTFNO6JmFLcILHcN6/uIb+OW+HWZrGBvMJCSl5zwCtLFQ4U4KO TFmQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=mU5fOuFa0asJ8/RqiN8lVAPTh0kpPR9/MXoDY9LeyHk=; b=CBjMQOlhEFxyfsnQaEjRzWx/pt3tYQdOVUFA8r4GRZQL0Luw0BV4u8cxtOlT3U5QyX 3NRH6mxho+5vIIvc+sLEhFIsVQ34FsA9Ow6akk1+BXtaM+zB/7f02Kjt9vMJ4IY3uCrU hwReys88y96q87G5Yl9MFLxT1B6CNXwZ4Rgtv5F3DfmlNkrNKexkdALmt3djS2ou+j73 QZUexN+QTk61qX8cZtwh1TKD4F3wjibeTkIjBYLqsJP124o8Ntu/hAdBuIPPnRu0y5YZ h2xe8kAWS1GAVGYCv38Dpwe//S6IIf2W8l47Vu3umgf1Expl6q6JSDtaDF2Pe3Ivjimb s+nA== X-Gm-Message-State: AOAM530rrUkfcZhLjZtYgJalNVSfHq6oHJ/BYqfmyqawivskJvzb1f22 4FxFFC9IgY7bDz8tX+ahmJP8MdRZlKGYr2cn17YUSg== X-Google-Smtp-Source: ABdhPJxPI6/02NA2C2URvt6N/CcW5tUaanj295wfDsb175OGHpFuvt7IgBI5KqIvDDwaDlUL4KY+sOn0VnccFedaZu8= X-Received: by 2002:a17:906:8a65:: with SMTP id hy5mr19918109ejc.250.1615285224048; Tue, 09 Mar 2021 02:20:24 -0800 (PST) MIME-Version: 1.0 References: <20210309032637.41778-1-j@getutm.app> In-Reply-To: From: Peter Maydell Date: Tue, 9 Mar 2021 10:20:07 +0000 Message-ID: Subject: Re: [PATCH] coroutine: add libucontext as external library To: Joelle van Dyne Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=2a00:1450:4864:20::62e; envelope-from=peter.maydell@linaro.org; helo=mail-ej1-x62e.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: Kevin Wolf , Paolo Bonzini , =?UTF-8?Q?Daniel_P=2E_Berrang=C3=A9?= , QEMU Developers , Stefan Hajnoczi Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, 9 Mar 2021 at 09:59, Joelle van Dyne wrote: > > On Tue, Mar 9, 2021 at 1:36 AM Daniel P. Berrang=C3=A9 wrote: > > The README here: > > > > https://github.com/kaniini/libucontext > > > > indicates that it is intentionally limiting what registers it saves > > and restores, explicitly excluding FPU. > > > > Peter & Paolo expressed concern about this, indicating FPU reg support > > was a requirement for QEMU: > > > > https://lists.gnu.org/archive/html/qemu-devel/2021-01/msg05525.html > > > Does it make a difference if this is provided as an option and not as > a replacement? Would it make sense to add some warning at configure > time? Right now none of the concurrency backends are supported on iOS > and it's possible support will go away on macOS as well in the future. > QEMU would not be able to run at all. We don't currently support iOS; if we add it we definitely don't want to add it as a "we know this has buggy coroutine support" target, because that's a path to weird hard-to-diagnose bugs. Right now macOS works fine without libucontext; if we ever do need to use libucontext on macOS in future we'd want to get the FPU support etc fixed first. Adding FPU handling for aarch64 to libucontext should not be too difficult (because the FPU is guaranteed to exist you don't need to do the hardware capability detection the README talks about). thanks -- PMM