Re: [Qemu-devel] [PATCH v7 1/4] isapc: Fix non-KVM qemu boot (read/write memory for isapc BIOS)

[Jordan Justen]

On Thu, May 30, 2013 at 7:06 PM, Kevin O'Connor <address@hidden> wrote:
> On Wed, May 29, 2013 at 01:27:24AM -0700, Jordan Justen wrote:
>> The isapc machine with seabios currently requires the BIOS region
>> to be read/write memory rather than read-only memory.
>>
>> KVM currently cannot support the BIOS as a ROM region, but qemu
>> in non-KVM mode can. Based on this, isapc machine currently only
>> works with KVM.
>>
>> To work-around this isapc issue, this change avoids marking the
>> BIOS as readonly for isapc.
>
> How about changing the code to always make the ROM read/write (instead
> of doing it only on isapc).  Currently, if the rom is marked as
> read-only, then SeaBIOS makes it read/write as the first thing it
> does.  So, making it read-only doesn't really serve any purpose.

Are you talking about PAM registers? I think these should only affect
0xe0000-0xfffff and 0xfffe000-0xffffffff. So, the PAM registers should
only impact part of the potential ROM range.

Also, I think the PAM registers should default to ROM mode after reset
and on power-on.

-Jordan