On 03/24/10 23:28, Juan Quintela wrote:
Humm, I think it means. Can you migrate from a "new" vga to an old one,
and maintain it working?
Depends on the vgabios version.
vgabios 0.6c will not support vesa gfx modes on older qemu, no matter
whenever you started fresh or migrated to it.
- s->vbe_regs[VBE_DISPI_INDEX_ID] = VBE_DISPI_ID0;
+ s->vbe_regs[VBE_DISPI_INDEX_ID] = VBE_DISPI_ID5;
+ s->vbe_regs[VBE_DISPI_INDEX_VIDEO_MEMORY_64K] = s->vram_size / (64 * 1024);
After migration, vbe_regs[VBE_DISPI_INDEX_ID] would have the value
VBE_DISPI_ID5, but vbe_regs[VBE_DISPI_INDEX_VIDEO_MEMORY_64K] will have
any random value, no?
vgabios uses both once at init time. resetting vga will reset the vbe
regs too. So when migrating from new to old qemu: Before reset vgabios
will have the video memory size saved somewhere. After reset ID will
reset to ID0, and in case you are running vgabios 0.6c vesa gfx modes
will stop working.
cheers,
Gerd
