Re: Sparc32 not working:2.6.23-rc1 (git commit1e4dcd22efa7d24f637ab2ea3a77dd65774eb005)

From: Mark Fortescue
Date: Sun Jul 29 2007 - 14:26:45 EST




On Sun, 29 Jul 2007, Krzysztof Helt wrote:

On Sun, 29 Jul 2007 00:21:06 +0100 (BST)
Mark Fortescue <mark@xxxxxxxxxxxxxxxxxx> wrote:

Hi Krzysztof,

There have been lots of changes to the DMA system (git bisect is not
viable form my working 2.6.22 kernel as the dma changes kill the build for
over half the posible commits to check). It could be a side effect of
these changes.


It is not DMA I suppose. It does not happen in any specific place. It is easy to trigger by loading
and unloading the sunlance module, but it hangs linux in other places (init process, console login).

It happens only in SMP. If it happens in the sunlance module it happens in sparc_lance_probe_one()
(in probing function). I thought it is due to openprom accesses so I commented them out (and put
hardcoded values there). No real change. It is always in the probe_one method before any DMA is
started.

Sometimes it drops me to the prom prompt. I am not very experienced so I was able only to find (ctrace) that
the prompt was called in the method spwin_bad_ustack_from_kernel() which got there from mna_handler
(misaligned access) through kernel_unaligned_trap(). I don't know which function triggered the
unaligned access. The %o register values sent to the kernel_unaligned_trap() are outside addresses
from System.map and outside addresses of loaded (or just loaded the sunlance) modules.

This is where I need help. How can I find where the misaligned access happened?


The is a memory corruption issue on Sparc32 - sun4c (I am going to try and track it done over the next few days). It sounds like it may affect more than just sun4c issue.

Try going back to v2.6.22 and then appling f61698e6489f229f9fcfe29e68f228389a772993 - memset.S error, 196bffa5dc3181897bd32e41415ec0db8dbab5e7 - entry.S delay loops,
f3c681c028846bd5d39f563909409832a295ca69 - Serial Console Locking

(My last working kernel is v2.6.22 Commit
eb6bf6bfb580afaf1e1a1d30cba17a078530cf4 with the first of the above two patches applied and some additional ones that fix verious sun partition/UFS filing sustem issues).

I am going to try to cherry pick a set of commits to see if I can't get a better idear of where the memory corruption on sun4c is coming from. Build problems sue to the DMA changes make git bisecting un-usable untill I have found out which patches fix the DMA build issues.

Regards,
Krzysztof
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