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[170.10.129.124]) by mx.google.com with ESMTPS id q3-20020a37f703000000b007223bb531aasi6703981qkj.726.2023.03.06.06.58.46 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 06 Mar 2023 06:58:46 -0800 (PST) Received-SPF: pass (google.com: domain of berrange@redhat.com designates 170.10.129.124 as permitted sender) client-ip=170.10.129.124; Authentication-Results: mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=iJUw5ZN2; spf=pass (google.com: domain of berrange@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=berrange@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1678114726; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=a93oAn60717NX8pmLmU53M4NQQZCFhxdTP7eNfQ6xsA=; b=iJUw5ZN2k8lVWhXuxbjbLUj/WOeAuP2i7swJsWBlM/Iprg3zFnFiAF/ta/qsAQhzWH/+Ju OT5fckulQsP66Kibz4vD2aHemdarrnlBe+jXTKTHHM6v7kQwGJT7Yo4j75POt80dmpL8+4 VTS4ECJiFuOwkWdx7IByBZWxV8SpSeY= 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-563-MPXax0aiPU--pOq_go1idA-1; Mon, 06 Mar 2023 09:58:45 -0500 X-MC-Unique: MPXax0aiPU--pOq_go1idA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 82EC7811E6E; Mon, 6 Mar 2023 14:58:44 +0000 (UTC) Received: from redhat.com (unknown [10.33.36.53]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7E2962026D4B; Mon, 6 Mar 2023 14:58:38 +0000 (UTC) Date: Mon, 6 Mar 2023 14:58:30 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Thomas Huth , Peter Maydell , libvir-list@redhat.com, John Paul Adrian Glaubitz , Richard Henderson , qemu-devel@nongnu.org, Markus Armbruster , Wilfred Mallawa , qemu-arm@nongnu.org, Reinoud Zandijk , xen-devel@lists.xenproject.org, Paolo Bonzini , Maxim Levitsky , Alex =?utf-8?Q?Benn=C3=A9e?= Subject: Re: [PATCH v4 2/5] docs/about/deprecated: Deprecate the qemu-system-i386 binary Message-ID: Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= References: <20230306084658.29709-1-thuth@redhat.com> <20230306084658.29709-3-thuth@redhat.com> <7f1501ba-f875-b227-8d7e-f43e69b2ab8d@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 10.11.54.4 X-TUID: yOM9dZWavbdJ On Mon, Mar 06, 2023 at 02:25:46PM +0000, Daniel P. Berrangé wrote: > On Mon, Mar 06, 2023 at 03:18:23PM +0100, Thomas Huth wrote: > > On 06/03/2023 15.06, Daniel P. Berrangé wrote: > > > On Mon, Mar 06, 2023 at 02:48:16PM +0100, Thomas Huth wrote: > > > > On 06/03/2023 10.27, Daniel P. Berrangé wrote: > > > > > On Mon, Mar 06, 2023 at 09:46:55AM +0100, Thomas Huth wrote: > > > > > > [...] If a 32-bit CPU guest > > > > > > +environment should be enforced, you can switch off the "long mode" CPU > > > > > > +flag, e.g. with ``-cpu max,lm=off``. > > > > > > > > > > I had the idea to check this today and this is not quite sufficient, > > > > [...] > > > > > A further difference is that qemy-system-i686 does not appear to enable > > > > > the 'syscall' flag, but I've not figured out where that difference is > > > > > coming from in the code. > > > > > > > > I think I just spotted this by accident in target/i386/cpu.c > > > > around line 637: > > > > > > > > #ifdef TARGET_X86_64 > > > > #define TCG_EXT2_X86_64_FEATURES (CPUID_EXT2_SYSCALL | CPUID_EXT2_LM) > > > > #else > > > > #define TCG_EXT2_X86_64_FEATURES 0 > > > > #endif > > > > > > Hmm, so right now the difference between qemu-system-i386 and > > > qemu-system-x86_64 is based on compile time conditionals. So we > > > have the burden of building everything twice and also a burden > > > of testing everything twice. > > > > > > If we eliminate qemu-system-i386 we get rid of our own burden, > > > but users/mgmt apps need to adapt to force qemu-system-x86_64 > > > to present a 32-bit system. > > > > > > What about if we had qemu-system-i386 be a hardlink to > > > qemu-system-x86_64, and then changed behaviour based off the > > > executed binary name ? > > > > We could also simply provide a shell script that runs: > > > > qemu-system-x86_64 -cpu qemu32 $* > > > > ... that'd sounds like the simplest solution to me. > > That woudn't do the right thing if the user ran 'qemu-system-i386 -cpu max' > because their '-cpu max' would override the -cpu arg in the shell script > that forced 32-bit mode. It would also fail to work with SELinux, because policy restrictions doesn't allow for an intermediate wrapper script to exec binaries. 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 :|