From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jan Beulich" Subject: RE: [PATCH] CPUID level 0x00000007:0 (ebx) is word 9, instead of word 7 Date: Wed, 01 Jun 2011 07:35:57 +0100 Message-ID: <4DE5F9ED0200007800044BCD@vpn.id2.novell.com> References: <4DE501230200007800044777@vpn.id2.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Xin Li Cc: Keir Fraser , xen-devel List-Id: xen-devel@lists.xenproject.org >>> On 31.05.11 at 16:59, "Li, Xin" wrote: >> can't see why we would need to stay in sync with Linux's capability >> array indices. >=20 > why? Typically we reuse Linux code unless Xen has its special logic. So you would suggest leaving indices 7 and 8 unused instead? Looking at current Linux, we certainly could convert Xen to use index 8 for virtualization features, but since these are being tracked differently already anyway I don't see a value in this. As to index 7, just look at ARAT - we're already diverging from Linux here (having it allocated in index 3). Bottom line is that I think keeping the names (and in various cases the grouping together, namely when the bits are grouped together in some CPUID leaf's output) in sync is desirable, but following Linux to the bit doesn't always make sense. After all, some thinking will always be necessary when porting over patches. Jan