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=-3.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 68011C64E8A for ; Wed, 2 Dec 2020 17:45:54 +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 8B7FA221FB for ; Wed, 2 Dec 2020 17:45:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8B7FA221FB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bugs.launchpad.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:39346 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kkWCM-0001Z3-6L for qemu-devel@archiver.kernel.org; Wed, 02 Dec 2020 12:45:50 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:36962) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kkW7b-0006NG-M2 for qemu-devel@nongnu.org; Wed, 02 Dec 2020 12:40:55 -0500 Received: from indium.canonical.com ([91.189.90.7]:32970) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1kkW7Z-0002aj-Hv for qemu-devel@nongnu.org; Wed, 02 Dec 2020 12:40:55 -0500 Received: from loganberry.canonical.com ([91.189.90.37]) by indium.canonical.com with esmtp (Exim 4.86_2 #2 (Debian)) id 1kkW7Y-0005oL-9S for ; Wed, 02 Dec 2020 17:40:52 +0000 Received: from loganberry.canonical.com (localhost [127.0.0.1]) by loganberry.canonical.com (Postfix) with ESMTP id 4140F2E80E1 for ; Wed, 2 Dec 2020 17:40:52 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Date: Wed, 02 Dec 2020 17:34:37 -0000 From: Alex Coplan <1906536@bugs.launchpad.net> To: qemu-devel@nongnu.org X-Launchpad-Notification-Type: bug X-Launchpad-Bug: product=qemu; status=New; importance=Undecided; assignee=None; X-Launchpad-Bug-Tags: arm linux-user X-Launchpad-Bug-Information-Type: Public X-Launchpad-Bug-Private: no X-Launchpad-Bug-Security-Vulnerability: no X-Launchpad-Bug-Commenters: alecop philmd pmaydell X-Launchpad-Bug-Reporter: Alex Coplan (alecop) X-Launchpad-Bug-Modifier: Alex Coplan (alecop) References: <160692480491.27592.13493676422712150173.malonedeb@chaenomeles.canonical.com> Message-Id: <160693047732.27532.16929573524978856322.malone@chaenomeles.canonical.com> Subject: [Bug 1906536] Re: Unable to set SVE VL to 1024 bits or above since 7b6a2198 X-Launchpad-Message-Rationale: Subscriber (QEMU) @qemu-devel-ml X-Launchpad-Message-For: qemu-devel-ml Precedence: bulk X-Generated-By: Launchpad (canonical.com); Revision="55c41fea591e042b8bb54e6952942f55c764435e"; Instance="production" X-Launchpad-Hash: 3a878be45dda4a2d6f8fb8e02842c9d7f6f02e07 Received-SPF: none client-ip=91.189.90.7; envelope-from=bounces@canonical.com; helo=indium.canonical.com X-Spam_score_int: -65 X-Spam_score: -6.6 X-Spam_bar: ------ X-Spam_report: (-6.6 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.25, RCVD_IN_DNSWL_HI=-5, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Bug 1906536 <1906536@bugs.launchpad.net> Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi Philippe, I'm aware of the prctl workaround. It seems to me that this is clearly a regression in functionality. Prior to the change, I could test any executable with any vector length without having to modify the executable. Now I have to insert a prctl to test with 1024 or 2048-bit SVE vectors? Moreover, with this change, it's no longer possible to have the wider VL inherited across exec() to another QEMU instance. -- = You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1906536 Title: Unable to set SVE VL to 1024 bits or above since 7b6a2198 Status in QEMU: New Bug description: Prior to 7b6a2198e71794c851f39ac7a92d39692c786820, the QEMU option sve-max-vq could be used to set the vector length of the implementation. This is useful (among other reasons) for testing software compiled with a fixed SVE vector length. Since this commit, the vector length is capped at 512 bits. To reproduce the issue: $ cat rdvl.s .global _start _start: rdvl x0, #1 asr x0, x0, #4 mov x8, #93 // exit svc #0 $ aarch64-linux-gnu-as -march=3Darmv8.2-a+sve rdvl.s -o rdvl.o $ aarch64-linux-gnu-ld rdvl.o $ for vl in 1 2 4 8 16; do ../build-qemu/aarch64-linux-user/qemu-aarch64 = -cpu max,sve-max-vq=3D$vl a.out; echo $?; done 1 2 4 4 4 For a QEMU built prior to the above revision, we get the output: 1 2 4 8 16 as expected. It seems that either the old behavior should be restored, or there should be an option to force a higher vector length? To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1906536/+subscriptions