> 
> > At system startup time, the firmware is living in a known location in
> > VA space: that covered by the first L1 PTE.  Therefore, I squirrel
> > that away, and when necessary swap it with the 'normal' first L1 PTE
> > of the running process, do the firmware access, then swap it back.
> 
> Hmm, the PTE of the running process.

yeah.  it's expensive (translation buffer invalidate!) and ugly, but
it works.

That technique is only used on systems which don't have 'native'
console support.


cgd