The problem obviously only affect people that make use of
rh_alloc_fixed(), which is the case when you program an MCC or a QMC
controller of the CPM. Without the patch cpm_muram_alloc_fixed()
succeed when it should not, for example when trying to allocate out of
range areas or already allocated areas, so it is possible that buffer
descriptors or other control structures used by other controllers get
corrupted.
Digging into ooooold Linux (like 2.6.9, I haven't checked before),
the problem seems to always have been present.
Without this patch I experienced oops (sometimes panic, sometimes not)
in various unrelated part (probably an indirect result of either
corruption of rheap management structures or corruption caused by the
CPM using crazy overwritten data) and also initialization of
multi-channel control structures putting other communication
controllers out-of-order.
The only risk I can think off is that it could break some out of tree
kernel space code which worked because of luck and a double error -
for
example when doing a single DPRam allocation from offset 0 while
leaving an area reserved at the base of the DPRam. So I think it
should
be put in 2.6.28.
Paul are you planning on picking this up for .28 if not I'll pick it
up for .29
- k
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