> >No, just map an uncached, unbuffered memmory space for the PCI environment
> >and the problem will go away (if it is a cache related issue, that is...)
>
> It's not quite that simple. We already map PCI I/O and memory uncached. The
> difficulty with DMA-enabled network drivers is that they want to access main
> memory which obviously needs to be cached for performance reasons. So
> explicit synchronisation instructions are needed.
>
> We've previously kicked around the idea of adding a GFP_UNCACHED flag to
> __get_free_page to help with this but nobody has implemented it yet.
This doesnt help you in general. Having the ring buffer uncached on a lance
is the wrong solution (tm) for most platforms. Its better to flush the page
out of cache and push it to memory when writing. That gets you things like
burst writes.
Alan
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