Re: [RFC] I/O Access Abstractions

From: Alan Cox (
Date: Mon Jul 02 2001 - 17:15:27 EST

> - Parsing of this cookie on each inx/outx access, which can
> take a bit of time (typically looking up the host bridge)

It depends on the implementation obviously, but its typically something like

        take lock
        writew(port&0xFFFF, port&0xFFFF0000);
        writew(data, port&0xFFFF0000+1);
        drop lock

Assuming you can drop the bridges on 64K boundaries in pci mem space, or
one extra deref and a register load if not.

Can you give me an idea of what sort of cookie decoding a PPC/PMac would need
and why - Im working off things like pa-risc so I dont have a full picture.

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This archive was generated by hypermail 2b29 : Sat Jul 07 2001 - 21:00:10 EST