cb_dumpdata vs. PowerMac G5's (or at least my SSD context): add involvement of dumpinfo's maxiosize value?

[Justin Hibbits]

On 03/01/15 04:14, Mark Millard wrote:
> Context: 10.1-STABLE powerpc64 for PowerMac G5
>
> I'm unable to get panic dumps because the DMA size is rejected, 64K being too big. I'd like to get things to the point where panic dumps are possible for that context.

This was working in the original powerpc64 dump code.  Look at r257941, 
which was the original code that I committed.  I guess the DMA size 
clamping didn't get migrated to the new dump code.

- Justin