On Fri, 2012-03-16 at 16:44 +0000, Mark Cave-Ayland wrote:
Whilst looking at Jakub's bug report here
, I've been working on a
patch to correct the QEMU interrupt handler on qemu-ppc. Now that this
bug is close to being fixed, I've had a look at OpenBIOS to find out why
newer versions of OpenBIOS freeze before the HelenOS loading screen.
I observed that as well, it hangs some time during the display of
the boot messages.
A local git bisect shows that the culprit is actually
Author: laurent <laurent@f158a5a8-5612-0410-a976-696ce0be7e32>
Date: Tue Aug 4 21:08:37 2009 +0000
Allows to configure screen size from Qemu command line options
Only enabled for PPC/QEMU and VGA/VBE.
I'm surprised by that. This has worked well for a long time, I think
something else in qemu causes that commit to fail.
Having stepped through vga_vbe_init() in drivers/vga_vbe.c, the only
difference is that reading the display depth from the QEMU FW CFG
interface returns 15 instead of the in-built OpenBIOS default of 8.
AFAIK that's been working fine for a while...
So is a bit-depth of 15 supported by OpenBIOS? This
seems quite unusual
given that it is not a power of 2; however if I use GDB to override the
value to 16 then HelenOS boots but with a blue screen BIOS on VGA so I'm
not sure that is the correct solution either. Does anyone know what the
default bit-depth is in Apple's firmware?