Anthony Liguori wrote: > On 01/26/2010 08:44 AM, Jan Kiszka wrote: >> Hi, >> >> just received some Linux guest kernel that refuses to properly use its >> framebuffer console under QEMU (probably any version, tried down to some >> 0.10.x). It turned out that it has CONFIG_FB_CIRRUS enabled and fails to >> initialize the display when this is actually used. Anyone came across >> this before or has some idea what goes wrong? >> > > Looks like it worked at some point: > > commit ca896ef389fc44c7a673d1bd2b94823e28da37a1 > Author: aurel32 <aure...@c046a42c-6fe2-441c-8c8c-71466251a162> > Date: Thu May 8 12:21:27 2008 +0000 > > cirrusfb: proper "Attribute Controller Toggle Readback" register > behaviour > > (Marcelo Tosatti) > > > git-svn-id: svn://svn.savannah.nongnu.org/qemu/tr...@4386 > c046a42c-6fe2-441c > > The cirrusfb Linux driver uses the toggle readback register to determine > whether to flip 0xC30 to data/address mode. > > Without proper implementation the VGA mode will be erroneously set to > blank resulting in crashes when starting BITBLT. > > 3d4h index 24h (R): Attribute Controller Toggle Readback Register > bit 7 If set the Attribute Controller will next access a data register, if > clear it'll access the index register > > > Signed-off-by: Marcelo Tosatti<mtosa...@redhat.com> >
Yep, and 2bec46dc97571a3c34b18fe4ca198e7bfbdca41f broke it again. Unless Glauber immediately confesses the crime and removes the bug he left behind, I will try to understand the reason later. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux