[SeaBIOS] [HELP] The program cause screen mess

[Kevin O'Connor]

On Tue, Apr 21, 2015 at 12:23:15AM +0800, eJim Lee wrote:
> Yes, I have tried gtk_monitor+VGA+seaVGABIOS.

Did you see screen corruption when you tried gtk_monitor+VGA+seaVGABIOS?

> The following is my log:
> =====================================================
> LYJ-UPC:~/qemu$ ./build/x86_64-softmmu/qemu-system-x86_64 -enable-kvm
> -hda tmp/xp_rcc.append -hdb tmp/data.append -m 1024 -smp 1 -device
> VGA,romfile=/home/lyj/qemu/seabios/out/vgabios.bin -net none -chardev
> stdio,id=debugcon -device isa-debugcon,chardev=debugcon,iobase=0x0402
> SeaBIOS (version rel-1.7.5-0-ge51488c-20140602_164612-nilsson.home.kraxel.org)
[...]
> set VGA mode 143
> VBE current mode=4143
> VBE mode info request: 4143
>                                                        <---- start wbc
> set VGA mode 3
> set VGA mode 3
>                                                        <---- exit wbc
> VBE mode set: 4143
> set VGA mode 143
> VBE current mode=4143
> VBE mode info request: 4143
> qemu: terminating on signal 2

Was there screen corruption during the above log?

> I debugged both vgabios and qemu, and found the wbc didn't use vgabios
> interface but changing vgabios caused that the wbc run better.
> I found the wbc r/w vga register directly to set vga mode when added
> printf on vga_update_display in qemu.
> Uncomfortably, gfx_write_char have never been invoked and I deleted it
> in vgafb_write_char, that bring screen looking better. What happend? I
> can't understand.

I would guess the defect has some randomness to it and minor changes
to code layout can cause or avoid the problem.

> 
> Kevin, did you repeat screen mess?

I've tried several different configurations (including the last
command line you sent), but I have not been able to reproduce any
screen corruption.

-Kevin