[SeaBIOS] [PATCH] mark VBE mapping as reserved in e820

Kevin O'Connor kevin at koconnor.net
Sun Jan 24 01:03:46 CET 2010

On Sun, Jan 24, 2010 at 01:35:21AM +0200, Izik Eidus wrote:
> On Sat, 23 Jan 2010 18:10:37 -0500
> "Kevin O'Connor" <kevin at koconnor.net> wrote:
> > What is special about 0xe0000000 that the OS can't map pci devices
> > there?  Normal machines don't treat 0xe0000000 as special, why does
> > the VBE device require that?
> From the last time I looked on the code 0xe0000000 was the LFB address,
> LFB is used by vesa devices as the framebuffer memory area,
> this mean that vesa devices (not the case for vga) will try to map this
> 0xe000000 physical memory.

Okay, but why does the device hardcoded 0xe0000000 - why doesn't it
use a PCI bar?  A PCI bar should also be sufficient to stop the OS
from mapping two things to the same address, and it has the advantage
of not requiring special code in the BIOS.


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