Re: [Qemu-devel] Re: POST failure (loop) with isapc and seabios

[Sebastian Herbszt]

Gleb Natapov wrote:
> On Sun, Nov 22, 2009 at 04:07:56PM +0100, Sebastian Herbszt wrote:
> > Gleb Natapov wrote:
> > >May be make qemu to map it writable if isapc is specified.
> >
> > I don't think keeping the segment writable after POST is a good idea.
> Isn't it writable now after POST with pcipc? Why this is not a good
> idea?

seabios got this in src/post.c:
   // Allow writes to modify bios area (0xf0000)
   make_bios_writable();
   // Perform main setup code.
   post();
...
   // Write protect bios memory.
   make_bios_readonly();

The names and comments are kind of misleading since make_bios_writable()
and make_bios_readonly() both seem to also affect the option roms.

Bad things could happen if someone modifies the BIOS because it's unprotected
(e.g. VM crash).

- Sebastian