Re: [RFC] new bus architecture (+ byte-endianess)
H. Peter Anvin (hpa@transmeta.com)
7 Jun 1999 17:49:22 GMT
Followup to: <199906071643.JAA07209@pizda.davem.net>
By author: "David S. Miller" <davem@redhat.com>
In newsgroup: linux.dev.kernel
>
> Date: Mon, 7 Jun 1999 18:03:06 +0200
> From: Jakub Jelinek <jj@sunsite.ms.mff.cuni.cz>
>
> I don't know if SBUS<->SBUS DMA actually works, there are some bits
> for it but have never tried, but PCI<->other PCI should definitely
> work.
>
> SBUS<-->SBUS on the same segment works, I've tried it.
>
> One thing which probably does not work is PCI<-->PCI on the same PCI
> controller yet different PBM segments, at least sun PCI docs describe
> it this way. It seems the PCI controller cannot handle if it sends
> out a transaction to the system bus which is addressed back to itself.
>
That sounds like a Sun PCI bug... there is something in PCI which is
called "peer host bridges" which can talk to each other across the
host bus. The bus trees hanging off the various peer host bridges
have disjoint bus numbering.
-hpa
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