James Bottomley wrote:
On Thu, 2008-02-14 at 11:56 -0600, Mike Christie wrote:
You really don't want to do this. That signals to the block layer that
we have an iommu, although it's practically the same thing as a 64 bit
DMA mask ... but I'd just leave it to the DMA mask to set this up
correctly. Anything else is asking for a subtle bug to turn up years
from now when something causes the mask and the limit to be mismatched.
I thought BLK_BOUNCE_ANY just meant "don't bounce anything" (that was
from the blkdev.h comments).
It does ... that's why it's used in the IOMMU case ... and why it's
practically the same as a 64 bit mask.
We used it for iscsi_tcp because the network layer can take any type
of page and will do the right thing for the hardware it eventually
gets sent to.
Right, to you it means never bounce because net wants to do it instead.
However, I don't think that's the case for iSER, is it? ... as in, if
I will leave that to Roland and them :)
My only concern with a simple patch to use the ib interface's dma values
would be, if there is some event that causes us to start using inteface
ib0 then switch to ib1 (maybe like some sort of route table change if
that is possible), then we will have to loop over all the scsi devices's
queues and update the dma values. And if there is IO already queued then
would we have to possible rebuild those commands if something like the
dma_mask changed?
I've got the pathway tracing correct, it just goes to the infiniband
device and gets mapped there. If there's a mask mismatch (very
unlikely, I know) we get a very subtle and hard to trace error.
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