[SeaBIOS] cbvga

Kevin O'Connor kevin at koconnor.net
Tue Sep 30 21:03:02 CEST 2014

On Tue, Sep 30, 2014 at 12:40:26PM -0600, Marc Jones wrote:
> On Tue, Sep 30, 2014 at 7:06 AM, Kevin O'Connor <kevin at koconnor.net> wrote:
> > You don't see any output from SeaBIOS (no version banner and no boot
> > menu prompt)?
> >
> > Is the framebuffer really at 0xc0000000 (as the log reports) or at
> > 0xb8000 (as your question states)?  In my tests grub uses int10
> > instead of 0xb8000, but if it detects a vbe adapter it will setup a
> > graphical framebuffer and then write to that.  Do you see seavgabios
> > debug messages showing grub probing for vbe later in the log?  Is the
> > grub output you do see in graphics mode or text mode?
> I don't get any output from SeaBIOS. The framebuffer is at 0xc0000000.
> I asked about b8000 since that is the legacy area and I wasn't certain
> how grub does things. I didn't capture any additional ouptut while
> grub was loading. I assume that it is doing the vbe setup as you said.
> I can do some additional debug and instrument the int10s.

If the framebuffer is at 0xc0000000 then I'm surprised that you're not
getting output - the cbvga code is pretty simple once the framebuffer
is found.  I'd try increasing the debug level to 8 and recompile

Also, you might want to make sure that the framebuffer wasn't turned
off by something, and that some other vga option rom didn't get run
after cbvga.

Another random thing to check would be if cbvga is writing black on
black for some reason.  Also, make sure you have a recent version of
SeaBIOS - as I think f6b44b81e is needed.


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