switching linux kernels

		Hi All,

		I am switching to HardHat 2.2.13 from ppc 2.2.13.
		I have had good luck with everything except for one driver
that we have written.
		We have an hdlc driver that works fine with ppc, when I move
it to Hard Hat, all the bits are fine, we are not losing any data
whatsoever, just the data is corrupted some how.

		What could be going on? Uuggh.
		Thank you,
		--Julia

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Julia Elbert writes:

		I am switching to HardHat 2.2.13 from ppc 2.2.13.

No suggestions about your HDLC problem I'm afraid, but I suggest that you
switch to the 2.2.14 kernel from HardHat-1.2 (the latest) instead.  I just
noticed a nasty bug in fs/dcache.c:dcache_init in 2.2.13, which wastes 2Mb of
RAM on the dentry cache.  Not good in an embedded system, and it's fixed in
2.2.14.

Regards,
Graham
--
Graham Stoney
Principal Hardware/Software Engineer
Canon Information Systems Research Australia
Ph: +61 2 9805 2909  Fax: +61 2 9805 2929

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Julia Elbert wrote:

                I am switching to HardHat 2.2.13 from ppc 2.2.13.

.....whatsoever, just the data is corrupted some how.

Depending upon the flavor of the day ppc 2.2.13, it could be a cache
configuration difference.  The old 2.2.13 kernels often had the data
cache in the write-through mode to avoid a variety of bugs in both
hardware and software.

The HHLinux 2.2.13 (and all later kernels) run with copy-back data
cache and subsequent silicon errata fixes, so there may be a cache
coherency hole in the way your driver manages it's space.


	-- Dan

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