From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f169.google.com (mail-qt0-f169.google.com [209.85.216.169]) by mail.openembedded.org (Postfix) with ESMTP id F009E783E4 for ; Thu, 15 Jun 2017 16:38:09 +0000 (UTC) Received: by mail-qt0-f169.google.com with SMTP id c10so27504491qtd.1 for ; Thu, 15 Jun 2017 09:38:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=svjErx0qqyZrh1NoWJWMKPB2lG/Vumuk7w/0RcDEmFg=; b=Y/ZysARWhPJc8bE/0oTTiog0HO5gI1ptSsVJQQ4fBWUx5I2ilyaDMoo4DLAusMkMcX Fj/UK7RXt+d2b2pXxqSzVmQE45AqF0lt6Pm3+7H2/sxv4rAh5dDu7KpS1Hixb5YqYR8/ drDH9c4FPeyw3qvL+DOWHgG2TDjIsyCad4n77iqyBbg9Su6P3L4sxxAFLZaRfyf7euGe WUqHm3UzoSzsGf6iKmPeW9kbdTNFD2tcdPZ11/oN0NKQgU8uYFPm0xodLQlfdb3E15t4 fv4e7nV5iN6VyhMGgYxfJunJo1mc8QbYeb76u/IY3zAE21zx14O2d6jhgAGlhnkWm+ei /utg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=svjErx0qqyZrh1NoWJWMKPB2lG/Vumuk7w/0RcDEmFg=; b=Twx+Mzeu8v+fsuuELRZltK0MYL7ZdFGAvukpUe6PBP5uzEH1If4FhER2wZZfQWCoG7 s3co8kqyL90BGby6yocS7x65Iq9yW8TNcKYJYFADK9WCSFHv4triNxVrpzBm48Hyb1yF +Ne6lHMgxOX2Ho5IXnAsZKyfnK2sucrYBbUXjiy/M2JRHezT0SOjTBj4kKb3okbBQQH+ wcNXy1NlV8KIfG66oFnIrJ5xpv13fUZcgR0E/mrI9UfMZ09rPpsUOunN1bY0FF/LW3rB JREMumlBmnQnnziu81MRjC0NG5RX41v/0cNEmK7FvErOOzNd96Pe8nfMQykpzzf7JiWd RQtw== X-Gm-Message-State: AKS2vOzGVVzFxWbPZ+apl1RVEoAUmSQlrddzQQ9zdDgQKXb7++g/G3aY hjFiMQOFJgIw0uD3QAyY6O/ebO2jRXsv X-Received: by 10.55.31.162 with SMTP id n34mr7402300qkh.46.1497544690869; Thu, 15 Jun 2017 09:38:10 -0700 (PDT) MIME-Version: 1.0 Received: by 10.140.35.103 with HTTP; Thu, 15 Jun 2017 09:37:50 -0700 (PDT) In-Reply-To: <2607b2d4-c37f-5693-1002-db17f9e1024d@xevo.com> References: <1493752813-18913-1-git-send-email-mkelly@xevo.com> <2607b2d4-c37f-5693-1002-db17f9e1024d@xevo.com> From: "Burton, Ross" Date: Thu, 15 Jun 2017 17:37:50 +0100 Message-ID: To: Martin Kelly 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: Thu, 15 Jun 2017 16:38:10 -0000 Content-Type: multipart/alternative; boundary="001a1147e5f855bd110552024bf3" --001a1147e5f855bd110552024bf3 Content-Type: text/plain; charset="UTF-8" On 15 June 2017 at 17:17, Martin Kelly wrote: > 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 should > 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 host. > Since core2duo is very old by now, it should be fast for virtually everyone > building on x86. > 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. Ross --001a1147e5f855bd110552024bf3 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable

= On 15 June 2017 at 17:17, Martin Kelly <mkelly@xevo.com> wrote= :
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 should b= e fast as long as you run on a native CPU that is core2duo or better, as th= e native instructions can just be exposed and passed through to the host. S= ince core2duo is very old by now, it should be fast for virtually everyone = building on x86.

Right, I did some digging.=C2= =A0 Assuming you have KVM enabled then in the general case the -cpu option = is irrelevant as the instructions are handled natively. =C2=A0-cpu just cha= nges what CPUID flags the userspace sees, and so this is the Right Thing To= Do.

R= oss
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