Re: Updated 2.4 TODO List -- new addition WAS(test9 PCI resource collisions (fwd)

From: David S. Miller (davem@redhat.com)
Date: Tue Oct 24 2000 - 15:45:17 EST


   Date: Tue, 24 Oct 2000 13:50:10 -0700 (PDT)
   From: Linus Torvalds <torvalds@transmeta.com>

   Does the above make it work for you? I don't know if PCI even has
   the notion of transparent bridging, and quite frankly I doubt it
   does. The above would be nothing but a hack that basically says "I
   don't understand the resources of this bridge, so I'll just say it
   bridges everything".

I bet PCI allows no such thing, thus to be totally safe I would
conditionalize this feature on the specific bridge. Ie. only allow
it for this bridge type, because I bet it is just some bug in the
the address comparators which makes the bridge interpret zero ranges
as "forward and respond to everything".

This only would make sense if the bridge snooped config space access
to devices behind it, so that it knew what addresses to forward and
respond to. Just responding to "everything" would not work for
obvious reasons.

Actually, I think some other DEC bridges have this behavior too.
Maybe it's on purpose because many BIOS's dont init the bridge ranges
properly when doing address assignments.

Well, Linux-2.4.x does not do the assignments either (and this is why
certain Alpha systems do not work currently) :-) The 2.2.x
Alpha-specific Linux PCI code did init the bridge ranges, if I
remember correctly.

Later,
David S. Miller
davem@redhat.com
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