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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 5A1F7EB64D7 for ; Mon, 26 Jun 2023 09:36:36 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qDidx-00044j-H5; Mon, 26 Jun 2023 05:36:21 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qDidv-000447-ID for qemu-devel@nongnu.org; Mon, 26 Jun 2023 05:36:19 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qDidt-0002WY-QR for qemu-devel@nongnu.org; Mon, 26 Jun 2023 05:36:19 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1687772176; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+N44F6EbeW+cGZH7sx27tkQENl/aJfEu6zVzxCzFOx4=; b=Hi1gQUBjgMJx4NuRAq7In2mcTNd2fYNT8NtokcwU7ks76A7ayl2hFrAmT0bV7lKwa3dAhe oCFRu57Ah0L3mr3Uzt8CLcLDg7Z2c1jElH2SRtBcQnTpwBN7fXL3Zk+K73lau5NY9HT86m dB/tZcdoplIcpgDfpFUahDfaoJxmp1Y= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-132-ulByWGVJMmqobPFopcfVnQ-1; Mon, 26 Jun 2023 05:36:13 -0400 X-MC-Unique: ulByWGVJMmqobPFopcfVnQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 74F358CC203 for ; Mon, 26 Jun 2023 09:36:13 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.55]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 167FC40C6F5A; Mon, 26 Jun 2023 09:36:13 +0000 (UTC) Date: Mon, 26 Jun 2023 10:36:11 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Paolo Bonzini Cc: qemu-devel@nongnu.org Subject: Re: [PATCH v2 0/3] target/i386: allow using named CPU modeles with user mode emulation Message-ID: References: <20230626083317.144746-1-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/2.2.9 (2022-11-12) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=-1, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Mon, Jun 26, 2023 at 11:27:54AM +0200, Paolo Bonzini wrote: > On Mon, Jun 26, 2023 at 11:20 AM Daniel P. Berrangé wrote: > > > - for qemu-i386, the issue is that this emulator is restricted to running > > > programs on a 32-bit processor, even though it is actually emulating > > > programs that use the 32-bit kernel ABI on any processor. The behavior > > > the processor in compatibility (32-bit CS, EFER.LMA=1) mode is mostly > > > the same as when EFER.LMA=0 and the little code that is needed to handle > > > 64-bit ring-0 is even present in the qemu-i386 binary, just hidden > > > behind checks for HF_LMA_MASK. So, LM can also be treated as a feature > > > that is only relevant in kernel mode; not entirely, so this cannot yet > > > be extended to bsd-user, but the required changes are minimal. > > > > IMHO in this case we should hard block all named CPUs with > > 'lm' set from qemu-i386. It only makes sense to use named CPU > > models that were actually from the 32-bit era with qemu-i386. > > > > If someone wants Nehalem then they should be using qemu-x86_64. > > If someone wants qemu-i386 then they should be using an older > > named CPU model predating 'lm'. > > What you write is true for qemu-system-*, but the problem is that > qemu-user binaries are only able to run one ELF target. qemu-x86_64 is > not able to run i386 binaries, unlike a 64-bit kernel; and that's > really intrinsic in the design of qemu-user because implementing > multiple ABIs (including multiple definitions of structs and syscall > numbers) would require compiling the same files multiple times. Oh, right, yes, ignore my comment. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|