I'd like to address the issue of data caching on the ebsa285.
(kernel is 2.2.10-rmk2)
We have been running our ebsa285s with data caching off. With caching disabled
the stock ncr53c8xx SCSI driver works well and the lance ethernet driver works
nicely w/ a few changes. Everything falls apart, however, when we turn on
data caching. The NCR scsi shuts its self down after detecting
cache coherency problems, and the lance ethernet simply does not work.
In a naive attempt to solve the problem we've tried several combinations of
the following:
1.) There is a driver out there called bigphysmem; it allocates a fixed
chunks of memory at boot time and provides a malloc() interface to it.
We turn off caching on the sections managed by this driver.
We modified the scsi and ether drivers to use the bigphysmem malloc().
2.) we modified kmalloc et.al. to turn off caching on the
returned pages.
With any combination of these changes the kernel will boot
and the drives work reasonably well, but not 100%.
One class of problems seems to be that some file are corrupted.
for example the shell complains when it tries to source in
its config files:
bash: .: /etc/profile.d/lang.sh: cannot execute binary file
With caching turned off, the bigphysmem modified drivers
work as expected (it boots w/ no errors).
Finally to the questions:
1.) Is anybody actually running an ebsa285
with caching enabled ?
If so what type of changes are
required to the drivers ?
2.) Are we way off base here ?
Shouldn't the bigphysmem or changes to kmalloc()
solve the problem ?
What subtlety are we missing ?
--
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Inet Technologies Inc.
Plano, Texas
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