[coreboot] ADLO for buildrom

[Myles Watson]

> -----Original Message-----
> From: Uwe Hermann [mailto:uwe at hermann-uwe.de]
> Sent: Wednesday, April 30, 2008 1:49 PM
> To: Myles Watson
> Cc: 'Jordan Crouse'; 'Coreboot'
> Subject: Re: [coreboot] ADLO for buildrom
> 
> On Wed, Apr 30, 2008 at 01:31:33PM -0600, Myles Watson wrote:
> > There is very little duplicated here.  The ADLO in coreboot relies on
> > building the BOCHS bios from source with dev86, but the payloads/adlo
> uses
> > the new legacybios version.  The only thing that is exactly the same is
> one
> > of the elf headers.
> 
> Can you elaborate? I think I never heard of legacybios so far. What's
> the purpose and history and relation to ADLO of that? Does it _replace_
> ADLO completely or enhance it or... ? 

I would hope that soon we'll replace the loader from ADLO with one that can
be compiled with gcc as well.  Then it would completely supersede ADLO.

> Also, from a quick glance it
> doesn't seem to be written specifically for coreboot, what's the
> original purpose (just curious)?

Legacybios is the Bochs BIOS ported to compile on gcc instead of with the
dev86 tools.  Kevin's intent (I'm paraphrasing) was to make it easy to
update the BIOS so that more developers would be able to fix/improve it.  He
hoped that the ability to boot operating systems with BIOS callbacks would
make Coreboot more popular as well.

> Do you have a comparison between ADLO as in v2 svn vs. legacybios?

ADLO in v2 is based on a very old version of Bochs' BIOS that has many
timing problems (e.g., small loops that were supposed to wait until the CD
spun up.)  The new Bochs BIOS as compiled with dev86 is 128K, while Kevin's
version is 64K.  After compression with lzma this makes it very attractive
for a fallback payload to be able to boot from a rescue CD.

> Also note that legacybios is GPLv3, not sure if that's a problem
> for us. Do we link GPLv2 code against that?

I don't know very much about licensing issues.  I've copied Kevin on this
email.  Maybe he'll chip in.

Thanks,
Myles