From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35086) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ewlsx-0003JP-8c for qemu-devel@nongnu.org; Fri, 16 Mar 2018 05:42:52 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ewlsu-0006v9-66 for qemu-devel@nongnu.org; Fri, 16 Mar 2018 05:42:51 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:40356 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ewlsu-0006up-0o for qemu-devel@nongnu.org; Fri, 16 Mar 2018 05:42:48 -0400 Date: Fri, 16 Mar 2018 09:42:28 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Message-ID: <20180316094228.GC3066@redhat.com> Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= References: <20180314073000.3701-1-boqun.feng@intel.com> <20180314130130.GH17603@redhat.com> <20180316021157.GB3734@dragonstone.sh.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20180316021157.GB3734@dragonstone.sh.intel.com> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH] i386: add KNM cpu model List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Boqun Feng Cc: qemu-devel@nongnu.org, Paolo Bonzini , Eduardo Habkost , Richard Henderson On Fri, Mar 16, 2018 at 10:11:57AM +0800, Boqun Feng wrote: > On Wed, Mar 14, 2018 at 01:01:30PM +0000, Daniel P. Berrang=C3=A9 wrote= : > > On Wed, Mar 14, 2018 at 03:29:59PM +0800, Boqun Feng wrote: > > > A new cpu model called "KNM" is added to model Knights Mill process= ors. > >=20 > > Why the obscure acryonym? Can't we just call it KnightsMill so it is > > obvious what it is to everyone, as we've done for all other Intel > > CPU model names in the past. > >=20 >=20 > Ah.. my bad, good point! I will rename to "KnightsMill" in the next > version. >=20 > > > Compared to "Skylake-Server" cpu model, the following features are > > > added: > > >=20 > > > avx512_4vnniw avx512_4fmaps avx512pf avx512er avx512_vpopcntdq > > >=20 > > > and the following features are removed: > > >=20 > > > pcid invpcid clflushopt avx512dq avx512bw axv512cd clwb smap rtm > > > mpx xsavec xgetbv1 hle > >=20 > > "pcid" was one of the features critical to mitigate performance > > downside of the Meltdown bug fix in guests. Will Knights Mill have > > a fix for Meltdown in hardware, to avoid the need for split table > > pages and thus avoid the perf hit in guests ? > >=20 >=20 > I got the confirmation the Knights Mill doesn't have PCID at all. For > the alternative fix for Meltdown in hardware, I will ask around and inf= o > you if I get something. No need to wait for an answer to that question - if 'pcid' is not in hardware, we simply have to accept whatever the answer is. So just repost with the changed name. Regards, Daniel --=20 |: https://berrange.com -o- https://www.flickr.com/photos/dberran= ge :| |: https://libvirt.org -o- https://fstop138.berrange.c= om :| |: https://entangle-photo.org -o- https://www.instagram.com/dberran= ge :|