Re: [PATCH] sata_nv: fix ADMA ATAPI issues with memory over 4GB (v3)

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Robert Hancock wrote:
Jeff Garzik wrote:
Robert Hancock wrote:
This fixes some problems with ATAPI devices on nForce4 controllers in ADMA mode on systems with memory located above 4GB. We need to delay setting the 64-bit DMA mask until the PRD table and padding buffer are allocated so that they don't
get allocated above 4GB and break legacy mode (which is needed for ATAPI
devices).

Signed-off-by: Robert Hancock <hancockr@xxxxxxx>

This is a bit nasty :/

I would consider setting the consistent DMA mask to 32-bit, and setting the overall mask to 64-bit.

Seems like that would solve the problem?

The issue with that is that it would also constrain the ADMA CPB/PRD table allocation to 32-bit, which I'd rather avoid having to do. There are dual-socket Opteron boxes like HP xw9300 that use this controller, and limiting the allocation to 32-bit could force a non-optimal node allocation for the table memory.

These type of devices really want a version of dma_alloc_coherent that allows overriding the DMA mask for specific allocations to make this cleaner. I'm sure this isn't the only device that has different DMA mask requirements for different consistent memory allocations..

This patch does has the advantage of being confirmed to fix the reporter's problem (https://bugzilla.redhat.com/show_bug.cgi?id=351451) which there's something to be said for this late in the .24-rc series..


Also, does this need to be rebased on top of what I just pushed upstream?

It don't think so.. this change is independent from the "sata_nv: don't use legacy DMA in ADMA mode (v3)" patch you just merged.

This bug fix is still outstanding. I haven't heard any more comments on this one recently..

--
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@xxxxxxxxxxxxx
Home Page: http://www.roberthancock.com/

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