From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wei Liu Subject: Re: Limitation in HVM physmap Date: Fri, 1 Nov 2013 12:21:42 +0000 Message-ID: <20131101122142.GD4966@zion.uk.xensource.com> References: <20131018142012.GB20185@zion.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20131018142012.GB20185@zion.uk.xensource.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich , tim@xen.org, keir@xen.org Cc: George Dunlap , Stefano Stabellini , wei.liu2@citrix.com, Ian Campbell , xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On Fri, Oct 18, 2013 at 03:20:12PM +0100, Wei Liu wrote: > Hi Jan, Tim and Keir > > I currently run into the limitation of HVM's physmap: one MFN can only > be mapped into one guest physical frame. Why is it designed like that? > > The scenario is that: when QEMU boots with OVMF (UEFI firmware), OVMF > will first map the framebuffer to 0x80000000, resulting the framebuffer > MFNs added to corresponding slots in physmap. A few moments later when > Linux kernel loads, it tries to map framebuffer MFNs to 0xf00000000, > which fails because those MFNs have already been mapped in other > locations. Is there a way to fix this? > FWIW I tested this on real hardware, a Dell R710 server. dmesg: [ 39.394807] efifb: probing for efifb [ 39.437552] efifb: framebuffer at 0xd5800000, mapped to 0xffffc90013f00000, using 1216k, total 1216k [ 39.546549] efifb: mode is 640x480x32, linelength=2560, pages=1 [ 39.617140] efifb: scrolling: redraw [ 39.659709] efifb: Truecolor: size=8:8:8:8, shift=24:16:8:0 lspci -vvv: 0b:03.0 VGA compatible controller: Matrox Electronics Systems Ltd. MGA G200eW WPCM450 (rev 0a) (prog-if 00 [VGA controller]) Subsystem: Dell PowerEdge R710 MGA G200eW WPCM450 Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx- Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- SERR- Thanks > Wei