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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 6CBE3C07E95 for ; Fri, 16 Jul 2021 09:16:32 +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 2BDF761357 for ; Fri, 16 Jul 2021 09:16:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2BDF761357 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]:45296 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1m4JxP-0002Ja-AU for qemu-devel@archiver.kernel.org; Fri, 16 Jul 2021 05:16:31 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39776) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m4Jvw-0000To-EX for qemu-devel@nongnu.org; Fri, 16 Jul 2021 05:15:00 -0400 Received: from mail-ej1-x630.google.com ([2a00:1450:4864:20::630]:41954) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1m4Jvu-0002QX-JW for qemu-devel@nongnu.org; Fri, 16 Jul 2021 05:15:00 -0400 Received: by mail-ej1-x630.google.com with SMTP id go30so14118877ejc.8 for ; Fri, 16 Jul 2021 02:14:58 -0700 (PDT) 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; bh=cUErOJY+kLZvJn2yUui8U0AXkEdTFlAGHFM+/hh6yHw=; b=g/kfODtCE+EMjpB3cayVNRsk/UyZMPMfZd9VGAJagdcsRqHnNHp6O6W0NZh4SvGguV XEolWElhckhyvjXdoQcsruhQJg0s0V8uepdQryOQI6NgZ+6FAkCttXCHy27uZfSJgScA sySKnMSQ38Hf88CjyTGk3TEnCdDLugcEz6Zdisp8gJJFt1K1MRGT7CFZns78D/1gEvys iCHyC5jwzlDFnsOg9nDqtBaYUCXzHC0EtB/EDQ30e6IgM5Fx8fwri6De8ns/GOjXSugy ZE+u15u3ADR7cVCYnujv1SK1y9XXLoHDUA/JZCbTeuacJ6epyl7WQSVWb2zA3ar6/sen YtJw== 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; bh=cUErOJY+kLZvJn2yUui8U0AXkEdTFlAGHFM+/hh6yHw=; b=ng/wMhLVpZ4Jhwhx1jAbo6xbzLRv+5VGDDGf2SteiQdy4hPSd6BhJjD5wPyk5pvcGG uX2tc1m2QS36yVIhyDUEOW7k1RIj02h9LjcMhVDsVkKzdvD3tVpZF1JKSwlv4vsMHrKb f7X7EMDFzyb3xRJjH3VYbTXD7/J7LTRza/697zPUzocDpMmmH7Jw+K15/CK3n6hzzcnE L1C5z5K50GDvNMUsLdKiaVkr10591CKSGhu8Dt3C53I6mIBkz7P+EYhHqpa5yJPAZvHD GOFdDg8gSiX6aPJ5XtrE+VORSyO4TjGvUViL2hSN80mYOdIDlv89UeTILs61b9xbQNB1 bSPQ== X-Gm-Message-State: AOAM532zfHlS+uLa5X6gnZiR+e/wh5XJTztEcQ+sms7XHe+sL50gIe6G 0HetYo4a1gmEgpzs3LSDbktZX6xw/mdTWQVcT/xVNA== X-Google-Smtp-Source: ABdhPJzbTXBCCJ5ABkQ34dWEu8TfUlcWJJcyIK3CuSJ7z9VwrqGtfKrPt0XShBEfdiLWpft0LcD8vt5Mgf3UOcZkhpQ= X-Received: by 2002:a17:906:a108:: with SMTP id t8mr10550410ejy.407.1626426896826; Fri, 16 Jul 2021 02:14:56 -0700 (PDT) MIME-Version: 1.0 References: <20210714180635.1648966-1-richard.henderson@linaro.org> <20210714180635.1648966-3-richard.henderson@linaro.org> In-Reply-To: <20210714180635.1648966-3-richard.henderson@linaro.org> From: Peter Maydell Date: Fri, 16 Jul 2021 10:14:16 +0100 Message-ID: Subject: Re: [PATCH 2/2] target/arm: Add sve-default-vector-length cpu property To: Richard Henderson Content-Type: text/plain; charset="UTF-8" Received-SPF: pass client-ip=2a00:1450:4864:20::630; envelope-from=peter.maydell@linaro.org; helo=mail-ej1-x630.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: QEMU Developers Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, 14 Jul 2021 at 19:06, Richard Henderson wrote: > > Mirror the behavour of /proc/sys/abi/sve_default_vector_length > under the real linux kernel. We have no way of passing along > a real default across exec like the kernel can, but this is a > decent way of adjusting the startup vector length of a process. > > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/482 > Signed-off-by: Richard Henderson > +#ifdef CONFIG_USER_ONLY > +/* Mirror linux /proc/sys/abi/sve_default_vector_length. */ /proc/sys/abi/sve_default_vector_length wants a vector length in bytes, and it looks like we take a length in bits. I assume that's to match other places where the user can specify vector lengths, but we should mention the units we expect and that it's not what the kernel uses. We also don't support the kernel's (undocumented) "-1 means set to the maximum" behaviour -- do we need it, or is that more reasonably achievable by the user via other properties ? Otherwise Reviewed-by: Peter Maydell Regarding documentation, yeah, we don't have a great place to put usermode specific CPU properties. I would just put the documentation with the docs of the other properties. Maybe we'll sort out the document structure later (or at least put a link from the usermode doc section into the CPU part of the system-emulation doc section), but the usermode emulation documentation overall is in need of a massive overhaul some day... thanks -- PMM