From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jan Beulich" Subject: RE: [PATCH] small adjustment to asm constraints forc/s19400 Date: Tue, 31 Mar 2009 11:15:12 +0100 Message-ID: <49D20950.76E4.0078.0@novell.com> References: <8FED46E8A9CA574792FC7AACAC38FE7701D4B7A421@PDSMSX501.ccr.corp.intel.com> <8FED46E8A9CA574792FC7AACAC38FE7701D4B7A7D8@PDSMSX501.ccr.corp.intel.com> <49D0A942.76E4.0078.0@novell.com> <8FED46E8A9CA574792FC7AACAC38FE7701D4EAF926@PDSMSX501.ccr.corp.intel.com> <49D1FD66.76E4.0078.0@novell.com> <0A882F4D99BBF6449D58E61AAFD7EDD6101840E9@pdsmsx502.ccr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <0A882F4D99BBF6449D58E61AAFD7EDD6101840E9@pdsmsx502.ccr.corp.intel.com> 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: Guanqun Lu , Kevin Tian Cc: "xen-devel@lists.xensource.com" , KeirFraser List-Id: xen-devel@lists.xenproject.org >>> "Tian, Kevin" 31.03.09 11:47 >>> >Well, got your point. Those three SYSENTER MSRs are lost after resume. >We'll verify whether this is the only missing parts. BTW, in our box = 32-on >-32 S3 works fine, does that mean SYSENTER/SYSEXIT not used in pure >32bit pv environment, since in Xen 32bit path also misses that important >recovery? A 32-bit hypervisor does not expose sysenter to the guest (the feature bit gets cleared) - iirc this is to prevent the guest from thinking that using sysenter would provide a performance benefit. Hence restoring these MSRs in that case would only be needed if Xen itself made use of sysenter, = which however it doesn't (except for the now only theoretical case of the supervisor-mode-kernel feature). Jan