PCI hotplug + EEH issues

Todd Inglett tinglett at vnet.ibm.com
Wed Sep 11 05:56:22 EST 2002

On Tue, 2002-09-10 at 10:13, Benjamin Herrenschmidt wrote:
> >> How close is the OF code between ppc32 and ppc64 ? would it make
> >> some sense to clean up the internal representation of the device
> >> tree (which is, at least on ppc32, still closely tied to what I
> >> did with BootX) and move most of the OF interface code to some
> >> common location we could share ?
> >
> >Yes please! We should be able to start moving large bits of the OF
> >interface out to somewhere common. For example the ppc64 interrupt
> >parsing code is still buggy (its your original version), whereas on
> >ppc32 its fixed.
> Ok, so most of prom.c whould be janitor'ed & shared, right ?
> Where in the kernel tree can we put such common thing ?

Pete Bergner and I have talked about this a lot, but haven't had time to
go anywhere with it.  What we'd like is to not only share code, but to
move *all* of the Open Firmware code out of the kernel proper (i.e. into
a wrapper or probably zImage).  This isn't a new idea, of course, as it
has been discussed for ppc32 in the past -- I'm just not sure if it has
gone anywhere there either.

The zImage code would build the device tree as a data structure,
instantiate RTAS (if RTAS exists), initialize display devices, unpack
the kernel and pass control to the kernel with birecs for all these
things.  The kernel would either use the device tree data structure in
place as-is, or it would copy it and/or alter the structure as it sees
fit.  Since this code could be identical for ppc32 (in fact, it would
run in 32-bit even in our hardware) it would be nice to share code -- or
at least keep the code in sync.

Is this still a the idea over in ppc32-land, or has the thinking changed
over the past year or so? :)

If the code really is shared I'm not sure where it goes either.  For the
short term I wouldn't have a problem with just keeping it in sync.  It
would be annoying, but not difficult.


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