[parisc-linux] [PATCH] highmem_io for the sym53c8xx_2 driver??

[Grant Grundler]

Ryan Bradetich wrote:
...
> I am not sure what the highmem_io flag does, but when it is enabled it
> causes my C200 to HPMC.

That's for the SCSI midlayer to know whether or not the driver can do
64-bit DMA or not. Basically it means SCSI will use "page+offset"
instead of "address" when building SG lists.

All parisc machines require 32-bit DMA - ie through an IO MMU or direct.
Failures with highmem_io enabled suggests we aren't handling
"page+offset" correctly in the iommu code.

grant