From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel De Graaf Subject: Frame buffer mmap not working in pvops dom0 Date: Wed, 21 Jul 2010 09:47:57 -0400 Message-ID: <4C46FA8D.6040809@tycho.nsa.gov> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit 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@lists.xensource.com List-Id: xen-devel@lists.xenproject.org I'm trying to confirm the fix to the VESA fbdev mmap issue that was brought up a few months ago (http://marc.info/?l=xen-devel&m=126842551306571&w=2). The wiki page at http://wiki.xensource.com/xenwiki/XenPVOPSDRM says that this bug should be fixed, but doesn't point to a patch for the fix. I am still able to reproduce the issue both on real hardware and by running Xen under qemu (using cirrusfb on the dom0). Eamon (the original reporter) has also not been able to confirm a fix. I'm currently testing using Xen 4.1 built from hg 21831:6bebaf40e925 and a pvops dom0 from xen/stable-2.6.32.x revid c0a00fbe. So far, I've been able to determine that an mmap requesting multiple pages from /dev/fb0 will result in page table entries all pointing to the same physical page, which is not in the framebuffer address space. Writing to the mapped page ends up corrupting parts of kernel memory. I'd be happy to run further tests, try patches, or provide more information if needed. -- Daniel De Graaf National Security Agency