[Cbe-oss-dev] Context switching while page fault handling and warning

[Benjamin Herrenschmidt]

> This will exit as soon as _one_ of the 2 bits that compose
> MFC_CNTL_PURGE_DMA_COMPLETE is set, and one of them happens to be "purge
> in progress"... which means that we'll happily continue restoring the
> MFC while it's being purged at the same time.
> 
> The fix is something like:
> 
> 	POLL_WHILE_FALSE((in_be64(&priv2->mfc_control_RW) &
> 			 MFC_CNTL_PURGE_DMA_COMPLETE) ==
> 			MFC_CNTL_PURGE_DMA_COMPLETE);

So that was a bug but it still doesn't fix our problem... Playing around
in the various bits of the mfc context restore code does change the
problem though, we occasionally get a proper address (but we never get
the tag), that sort of thing...

Any expert on the actual chip around to tell us what else is wrong in
that MFC context save/restore code ?

Ben.