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

Izik Eidus ieidus at redhat.com
Sat Jan 23 22:30:33 CET 2010

On Sat, 23 Jan 2010 15:37:12 -0500
"Kevin O'Connor" <kevin at koconnor.net> wrote:

> On Sat, Jan 23, 2010 at 04:02:05PM -0200, Marcelo Tosatti wrote:
> > 
> > Izik, is this still needed? 
> > 
> > From: Izik Eidus <ieidus at redhat.com>
> > 
> > The vbe was not registered as reserved memory, and therefore windows was
> > able to try to map pci devices into this address range.
> > 
> > Signed-off-by: Marcelo Tosatti <mtosatti at redhat.com>
> It is not normal to add e820 entries for device memory.

This is true for pci and isa hot plug devices, but how in this case we can tell
the os not to map to this physical address pci devices?

If the range doesnt reserved I dont see how windows wont try to end up mapping
pci devices to there.

> not normal for a BIOS to add special mappings for video cards (how
> would it know what needed to be mapped).  One exception to this would
> be machines with built-in video adapters where the video ram is shared
> with system ram - however, in that case the memory area would almost
> certainly be at the end of ram and not at a fixed location.
> So, in general, this looks like a hack for VBE - can't we just fix
> this in the VBE code instead of adding it to the BIOS?
> -Kevin

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