> Hello,
>
> I've just recently signed up on the list, so bear with me, thanks.
>
> Dr . David Alan Gilbert wrote:
> >
> > At 04:21 PM 2/24/99 +0000, you wrote:
> > >Has anyone tried a PCNET AM79C971 based card on EBSA285 ?
> > >Mine doesn't works, it is detected by driver but sends nothing
> > >to the network
> >
> > As Phil said the problem is probably due to cache consistency (or the lack
> > of it)
> > on the EBSA.
> >
> > Intel, Alpha and SPARC PCI systems provide cache coherency between the PCI bus
> > and the processor - so if the Net card writes to main memory and then the host
> > looks at that location it will pretty much immediatly see the change.
> >
> > On systems based around the StrongARM/21285 combination if the location
> > happened to be previously in the processor cache then even after the write
> > by the net card, the processor will see the old value. This confuses the hell
> > out of the network drivers which presume they are on a system like Intel.
>
> This is a bit unfortunate? no?
No.
> Whats the root cause of this? the 21285's PCI implementation? or the SA?
Could be, but try out the modification suggested earlier first to
determine if it's cache related.
> Doesn't this mean that most (if not all) IO/DMA device drivers need
> patching to run on ARMLinux?
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...)
/Olof
Olof Backing Net Insight AB Phone: +46-8 449 22 36
Ingenj�rsv�gen 3, 2tr Fax: +46-8 449 22 40
S-117 43 Stockholm mailto:[EMAIL PROTECTED]
Sweden http://www.netinsight.se
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