Re: NFS root with cache on

[Jun Sun <jsun@mvista.com>]

Quinn Jensen wrote:
> 
> jsun@hermes.mvista.com wrote:
> 
> > Quinn Jensen wrote:
> >
> >>>> Is anyone else having trouble with NFS root on
> >>>> the 2.4.0 kernel?  It won't come up with the
> >>>> KSEG0 cache on unless I pepper the network driver
> >>>> with flush calls.
> >>>
> >>>
> >>> That's expected for most old network drivers that don't yet use tye
> he
> >>> new PCI DMA API documented in Documentation/DMA-mapping.txt.
> >>>
> >>> What driver is this?
> >>
> >> Both the stock 2.4.0 tulip and eepro100 drivers.  The
> >> problem doesn't happen when I go back to 2.3.99pre8.
> >>
> >
> > Did you set rx_copybreak to 1518?  I sent patches long time ago to the driver
> > authors for MIPS, but I am not sure they are not there.
> 
> Jun,
> 
> I have tried that in this case but it didn't help,
> because the receive skb data pointers all point to
> the KSEG0 view of the data anyway. 

I looked into similar problems a while back.  If I remeber correctly, the data
pointers do point to kseg0.  It is up to the driver to do appropriate
dma_cache_invalidate() (or some functions to that effect) at certain places.

What is the CPU?  It seems logical to suspect about the dma cache routines.

Jun