From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gerd Hoffmann Subject: VT/ioemu: vga memory access? Date: Tue, 16 May 2006 16:44:16 +0200 Message-ID: <4469E540.50900@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Return-path: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Xen devel list List-Id: xen-devel@lists.xenproject.org Hi, How is vga vram access handled in the device model? Is there some kind of notification system, by mapping those pages read-only, then trap and forward any write access to qemu-dm? I'm seeing obscure crashes in vga text mode, looks like they are triggered by a memmove in vga vram, at least this is what xenctx prints m= e: master-xen root /vm/hvm# /usr/lib/xen/bin/xenctx 35 eip: c01a59a9 esp: cf2dbe58 eax: c00b99a0 ebx: c00b99a0 ecx: fffff661 edx: c00b9860 esi: c00b8ec0 edi: c00b9000 ebp: c1207000 cs: 00000060 ds: 0000007b fs: 00000000 gs: 00000033 Stack: failed to map PT failed to map page. EIP c01a59a9 points into memmove (linux kernel): c01a5990 : c01a5990: 57 push %edi c01a5991: 39 d0 cmp %edx,%eax c01a5993: 56 push %esi c01a5994: 53 push %ebx c01a5995: 89 c3 mov %eax,%ebx c01a5997: 73 07 jae c01a59a0 c01a5999: e8 ca ff ff ff call c01a5968 c01a599e: eb 0c jmp c01a59ac c01a59a0: 8d 74 0a ff lea 0xffffffff(%edx,%ecx,1),%esi c01a59a4: 8d 7c 08 ff lea 0xffffffff(%eax,%ecx,1),%edi c01a59a8: fd std c01a59a9: f3 a4 repz movsb %ds:(%esi),%es:(%edi) ^^^^^^^^^^^^^^^^ here c01a59ab: fc cld c01a59ac: 89 d8 mov %ebx,%eax c01a59ae: 5b pop %ebx c01a59af: 5e pop %esi c01a59b0: 5f pop %edi c01a59b1: c3 ret Note that the edi register points to a page boundary and ecx looks bogous. Also note that "xm unpause", then xenctx again prints the very same register dump, feels like someone handling a fault incorrectly, leading to the very same fault instantly ... Idea anyone what this might be? cheers, Gerd --=20 Gerd Hoffmann Erst mal heiraten, ein, zwei Kinder, und wenn alles l=E4uft geh' ich nach drei Jahren mit der Familie an die B=F6rse. http://www.suse.de/~kraxel/julika-dora.jpeg