From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f194.google.com (mail-wr0-f194.google.com [209.85.128.194]) by mail.openembedded.org (Postfix) with ESMTP id 3110171A50 for ; Wed, 25 Apr 2018 19:54:34 +0000 (UTC) Received: by mail-wr0-f194.google.com with SMTP id v5-v6so3719671wrf.9 for ; Wed, 25 Apr 2018 12:54:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:date:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=jr7S7b2lyuUV7Oz6VKv/IvG6pvHo4Nqb1X93Ogg/EFQ=; b=FTdURORyaeUtectlsfMs9f1BjDbvjtppLAArc4IP5duZ20KcR4DwLt4y3gW+0kAjSH dkHj5Otot/LuHsiWuNljrrZRTs6jxrzuCra1EV+TfeBKmOd0lGzWHBf7D8u7I6X0Nlxk h7rIIsxL/gFDlywYyaZKVC6p3FCgwviBDokEztaiypOJTBh5pTyhPnGqlteg9KbR+3OJ 47m7id5KT67P5bK7/G3D1BcSX7el5bPw5nHXXpGk1vgbuFGMg9Q17kRjzz6WtsF1Uh1l XVghDrMnyPHxGKuJy7yrePfhfsPoDs3xfxFbPNToWcE0vV8ZsGqU+IpDu5TBJxpiLSCN gxew== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:date:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=jr7S7b2lyuUV7Oz6VKv/IvG6pvHo4Nqb1X93Ogg/EFQ=; b=GEnQEaCxubF6L5kkZ/unuFNOEZ9KPBB0dRt0VsVdgQ4ycMPSpWfSnkMYEMMwxhHheI MXLMbRWoIL8VqTEiY2ZH5FbrtniCLuSWMBmaEEi0v9WuJKRe7K2AFfNPpCrELr5iIva9 VeOuqAm/ssKX5WglC2B9gIqdhvnq67KN6c+PNQZh8stsALDwutVNMUv8nXIrKNbd9MBW qXUVbFsOpF4eO8mTOTTGDKIh/OfwKtgjsuhrgAttBFbfkR9JAWzOr6k82TK7nbbDIsCQ DLJnsT+e2//tFqJzemWsRj+WP9p4W6i3A+Ls5G0LTkebR5A6tLmu+gPM9Iu9FCFsqzNE CyOw== X-Gm-Message-State: ALQs6tBv9xnZz0BU9AlxQUQH0DuHNxJ3KdVRqRgyKzt8zHvURFBIXmsM eLRTswUfAZuazbrXLHYPAvw= X-Google-Smtp-Source: AIpwx4+xGltkMedyJ2dSZMtytQBIP8fOKulIEZDaMkPNzjNr9JMG8L2Jvh2tDxmOJziOMDwet8jePQ== X-Received: by 2002:adf:91c6:: with SMTP id 64-v6mr25208988wri.136.1524686075696; Wed, 25 Apr 2018 12:54:35 -0700 (PDT) Received: from localhost ([217.30.68.212]) by smtp.gmail.com with ESMTPSA id w40-v6sm25952753wrc.69.2018.04.25.12.54.34 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 25 Apr 2018 12:54:34 -0700 (PDT) From: Martin Jansa X-Google-Original-From: Martin Jansa Date: Wed, 25 Apr 2018 21:54:37 +0200 To: "Burton, Ross" Message-ID: <20180425195437.GA2244@jama> References: <1493752813-18913-1-git-send-email-mkelly@xevo.com> <2607b2d4-c37f-5693-1002-db17f9e1024d@xevo.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.9.5 (2018-04-13) Cc: Joshua G Lock , OE-core Subject: Re: [PATCH resend] qemuboot.conf: make cpus match built artifacts X-BeenThere: openembedded-core@lists.openembedded.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Patches and discussions about the oe-core layer List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 25 Apr 2018 19:54:35 -0000 X-Groupsio-MsgNum: 110764 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="HcAYCG3uE/tztfnV" Content-Disposition: inline --HcAYCG3uE/tztfnV Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Jun 15, 2017 at 05:37:50PM +0100, Burton, Ross wrote: > On 15 June 2017 at 17:17, Martin Kelly wrote: >=20 > > I am no expert, but running qemu -cpu help just says: > > > > kvm32 - "Common 32-bit KVM processor" > > kvm64 - "Common 64-bit KVM processor" > > > > My best guess is that, running on qemu without kvm, both cases will be > > slow (since it's all software emulation). But, using qemu -kvm, it shou= ld > > be fast as long as you run on a native CPU that is core2duo or better, = as > > the native instructions can just be exposed and passed through to the h= ost. > > Since core2duo is very old by now, it should be fast for virtually ever= yone > > building on x86. > > >=20 > Right, I did some digging. Assuming you have KVM enabled then in the > general case the -cpu option is irrelevant as the instructions are handled > natively. -cpu just changes what CPUID flags the userspace sees, and so > this is the Right Thing To Do. Sorry for replying to such old thread, but today I've noticed interesting s= ide-effect of this change. Today I was checking why starting qtbase examples in qemu fails with message about missing ssse3 support which which qtbase as compiled. The DEFAULT_TUNE in qemux86-64 is indeed set to core2-64 which supports ssse3, so qtbase is right to expect it in runtime. But then I was starting qemu manually (not with runqemu) with: qemu-system-x86_64 -M q35 -smp 4 -m 4G -net nic,model=3Dvirtio -net user,ho= stfwd=3Dtcp::2222-:22 -vga virtio -display sdl,gl=3Don -hda luneui-example-= image-qemux86-64-20180425152329-jama.rootfs.wic.vmdk -enable-kvm which defaults to using this kvm64 generic CPU which doesn't support ssse3 Changing it to qemu-system-x86_64 -M q35 -cpu core2duo -smp 4 -m 4G -net nic,model=3Dvirti= o -net user,hostfwd=3Dtcp::2222-:22 -vga virtio -display sdl,gl=3Don -hda l= uneui-example-image-qemux86-64-20180425152329-jama.rootfs.wic.vmdk -enable-= kvm gets rid of the message from qtbase, because core2duo supports ssse3 and ma= tches with qemux86-64, but my host CPU (AMD Bulldozer FX(tm)-8120), doesn't support the same cpu f= lags like core2due and qemu shows following message when starting: qemu-system-x86_64: warning: host doesn't support requested feature: CPUID.= 01H:EDX.ss [bit 27] EDX.ss is Self Snoop feature which is enabled in core2duo and few other QEm= u emulated CPUs, so I was looking on some other cpu I can emulate which has ssse3 while having the same flags= as my host's AMD cpu e.g. -cpu phenom is relatively close, but Bulldozer CPUs don't support 3dno= w, 3dnowext, so similar warning is shown. In the end I've switched to using -cpu Nehalem, which has ssse3, but doesn'= t enable CPUID_SS flag, now it starts without any warnings: qemu-system-x86_64 -M q35 -cpu Nehalem -smp 4 -m 4G -net nic,model=3Dvirtio= -net user,hostfwd=3Dtcp::2222-:22 -vga virtio -display sdl,gl=3Don -hda lu= neui-example-image-qemux86-64-20180425152329-jama.rootfs.wic.vmdk -enable-k= vm Regards, --=20 Martin 'JaMa' Jansa jabber: Martin.Jansa@gmail.com --HcAYCG3uE/tztfnV Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- iF0EARECAB0WIQRU+ejDffEzV2Je2oc3VSO3ZXaAHAUCWuDc/QAKCRA3VSO3ZXaA HEnSAJ9lnBATFBIT8xyl4gdvSV/SqDZZVACeMy2xJHOcC0AFpOkbQa4wihzvka4= =Zn6x -----END PGP SIGNATURE----- --HcAYCG3uE/tztfnV--