Re: [Etherboot-developers] Question on supporting nVidia .o driver

[Eric W B. <ebi...@ln...>]

Michael Brown <mb...@fe...> writes:

> On Wed, 21 Aug 2002, Andy Green wrote:
> > Over at the xbox linux project there is some discussion today about
> > supporting the nVidia inside the xbox (and used on nForce motherboards)
> > Ethernet controller with an etherboot driver.
> > The issue is that nVidia supply a .o file containing all the goodies; it
> >   is believed to be quite possible to fake up something using the kernel
> > network API to use this and make it believe it was a kernel driver.
> > The main question is, what's the prevailing opinion about using a .o in
> > this way GPL-wise.  It has been suggested that we'll be okay if we do
> > not distribute the .o but make our GPL project consist of everything
> > but.  (Because we are running on the xbox only, portability is not a
> > concern).
> > In addition, has anyone made such a fake kernel API shell before?  Has
> > anyone looked at supporting nForce motherboards?
> 
> Aside from the legal / copyright issues, a few technical points spring
> to mind:
> 
> 1. The nVidia .o file is 20kB in size - around 4-5 times the size of most
>    of the Etherboot drivers.  This might be enough to prevent it working
>    in 5.0.x (AFAICT, the memory-map changes in the 5.1.x branch will fix
>    this anyway).

This assumes the appropriate virt_to_bus, bus_to_virt and ioremap calls
are being made.  Otherwise it try reading and writing to the wrong
registers.

> 
> 2. Is it possible to use the .o file to create a polling driver?
>    Etherboot doesn't use interrupts.

Plus having code you can change is much more maintainable.

> 3. As others have said, don't bother faking a kernel network API - just
>    take the skeleton Etherboot driver in skel.c and fill out the gaps
>    between that and the nVidia .o file.

Eric