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

[Robert Hancock <hancockr@shaw.ca>]

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@shaw.ca>
> >
> > 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@nospamshaw.ca
Home Page: http://www.roberthancock.com/

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