[coreboot] SeaBIOS debug output

Eric W. Biederman ebiederm at xmission.com
Tue Jul 22 14:13:37 CEST 2008

Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net> writes:

> On 20.07.2008 22:57, ron minnich wrote:
>> On Wed, Jul 16, 2008 at 6:47 PM, Kevin O'Connor <kevin at koconnor.net> wrote:
>>> Hi Myles,
>>> On Wed, Jul 16, 2008 at 07:29:29PM -0600, Myles Watson wrote:
>>>>> Finding the option roms is easy - they are located between 0xc0000 and
>>>>> 0xe0000 and are 2KiB aligned.
>>>> That can be true after Coreboot copies them there.  Devices which have
>>>> option ROMs on the card are located somewhere in the PCI address space until
>>>> they are copied.  On-board devices have their option ROMs contained
>>>> somewhere in the BIOS chip.
>>> Right.  I'm a proponent of having coreboot be responsible for copying
>>> the option roms to their locations in ram.  Once coreboot loads the
>>> option roms then seabios can easily locate and run them
>> you're assuming they would all fit at one time into 64k. Not
>> necessarily the case. What has to happen is copy (or map) the rom, run
>> it, remove it, and so on. At least that's how I remember it working.
>> It was easier in the emulator as the copy step is not needed.
> If any of the option ROMs install interrupt handlers (video etc.) they
> may have to remain in memory after being run.

The space for options ROMS is 3*64K or 192K 0xc0000 0xd0000 0xe0000 with 0xf0000
consumed by the BIOS.

Further a well behaved option ROM will trim it's size after initialization
which allows you to pack in even more.

For coreboot this is a don't care.  For SEABIOS it is interesting.


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