From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jamie Lokier Subject: Re: [Qemu-devel] Re: expose host CPU features to guests Date: Sun, 9 Sep 2007 14:07:25 +0100 Message-ID: <20070909130725.GF24240@mail.shareable.org> References: <20070905174530.GA3945@karma.qumranet.com> <1189020371.7206.3.camel@squirrel> <20070907104738.GA14723@mail.shareable.org> <46E3A618.7030505@qumranet.com> <20070909124718.GE24240@mail.shareable.org> <46E3ED2B.6080606@qumranet.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel , qemu-devel-qX2TKyscuCcdnm+yROfE0A@public.gmane.org To: Avi Kivity Return-path: Content-Disposition: inline In-Reply-To: <46E3ED2B.6080606-atKUWr5tajBWk0Htik3J/w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Avi Kivity wrote: > Let's start with '-cpu host' as 'cpu host-cpuid' and implement '-cpu > host-os' on the first bug report? I have a feeling we won't ever see it. I have a feeling you won't ever see it either, but not because it's a missing feature. Instead, I think a very small number of users will spend hours frustrated that some obscure guest doesn't work properly on their obscure x86 hardware, then they will learn that they should not use "-cpuid host" for that guest on that hardware, even though it works fine with other guests, and then their problem will be solved (albeit at a cost), and seen as such an obscure combination that it might never be reported to Qemu developers. In other words, host-os is what _I'd_ implement because I care too much about the poor obscure users and think it's the safe option, but I'm not doing the implementing here ;-) If you are curious what the differences are, do this in a current Linux source tree: egrep -R '(set|clear)_bit\(X86_FEATURE' arch/{i386,x86_64}/kernel -- Jamie ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/