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From: "Burton, Ross" <ross.burton@intel.com>
To: Martin Kelly <mkelly@xevo.com>
Cc: Joshua G Lock <joshua.g.lock@intel.com>,
	OE-core <openembedded-core@lists.openembedded.org>
Subject: Re: [PATCH resend] qemuboot.conf: make cpus match built artifacts
Date: Thu, 15 Jun 2017 17:37:50 +0100	[thread overview]
Message-ID: <CAJTo0LavpmZCQPHSTrsuJwEZHLT2eAhKLQR8A7Fj3kX6BTC0wg@mail.gmail.com> (raw)
In-Reply-To: <2607b2d4-c37f-5693-1002-db17f9e1024d@xevo.com>

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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
> 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

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  reply	other threads:[~2017-06-15 16:38 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-02 19:20 [PATCH resend] qemuboot.conf: make cpus match built artifacts Martin Kelly
2017-05-22 17:29 ` Martin Kelly
2017-05-22 17:53   ` Randy Witt
2017-05-22 18:09     ` Martin Kelly
2017-06-13 16:44       ` Martin Kelly
2017-06-15 11:45 ` Burton, Ross
2017-06-15 16:17   ` Martin Kelly
2017-06-15 16:37     ` Burton, Ross [this message]
2018-04-25 19:54       ` Martin Jansa
2018-04-25 23:02         ` Martin Kelly
2018-04-25 23:11           ` Martin Jansa
2018-04-27 17:47             ` Martin Kelly

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