[LinuxBIOS] AMD Geode LX support for LinuxBIOS

[Jordan Crouse]

On 03/05/07 18:42 +0200, Stefan Reinauer wrote:
> * Uwe Hermann <uwe at hermann-uwe.de> [070503 12:01]:
> > > The VSA binary source is LGPL and is available at: 
> > > http://dev.laptop.org/git.do?p=geode-vsa
> > 
> > Wow! Now I'm impressed. This is really great news!
> 
> This code has been out for quite a while, and it is really great stuff
> although it will be hard for most LinuxBIOS developers to compile it
> themselfes. It means that we can build binary images in the build system
> and have them prepacked with the VSA code though, making deployment of
> LinuxBIOS for the Geode LX platform very easy for the users.
> 
> OFW does not use the VSA at all anymore (as far as I know, please
> correct me if I am wrong), since running the modules was slowing down
> the boot process quite a bit (compared to the rest of the boot time at
> least)

Reports of VSA slowness have been greatly exaggerated.  the main concern
is that its not compilable by mere mortals, so it can't be changed 
and optimized.  Once we have the VSA code ported to GNU tools, that will
be much easier.

Also, remember that the whole process was made easier by the fact that
OFW+OLPC is a very specialized platform - it just isn't intended to
change - so much so that we can hard code PCI BAR assignments and sizes.
Its a bit more difficult to implement this sort of process when you have
to worry about half a dozen different platforms that might implement 
slightly different models and scenarios. 

> So one question is in my mind: Can we implement the setup done by VSA 
> as native LinuxBIOS code, and does it make sense? What are the draw
> backs in such a scenario?

In a sanely operating system, you really need the SMM to handle the PCI
interaction - using a PCI spoofing system like OLPC does is useful for a
heavily embedded platform, but it really falls down for typical systems -
having something solid responding to CF8/CFC is way more re-assuring.
Once you agree to this, then most of VSA starts to make sense.  I agree,
a single binary blob that can't be hacked on is frustrating, but the
effort to change that is in progress.  I think that once its all GNUified,
everybody will be happy with it.

Jordan