Messages in this thread | | | Date | Wed, 23 Jan 2008 20:42:16 -0500 | From | Jeff Garzik <> | Subject | Re: sata_nv and 2.6.24 (was Re: fixed a bug of adma in rhel4u5 with HDS7250SASUN500G.) |
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Robert Hancock wrote: > Jeff Garzik wrote: >> Ping... sata_nv status is still a bit open for 2.6.24, and I would >> like to move us forward a bit. >> >> * Kuan's patch... it has been confirmed (and is needed), correct? >> can someone work up a good patch for 2.6.24? The only one I ever >> received was badly word-wrapped, and at the time, Robert seemed >> uncertain of it, so I waited. > > I can get you one later today hopefully. > >> >> * ADMA ATAPI 4GB issues... playing tricks with the ordering of >> allocations and DMA masks is just way too fragile. We just cannot >> guarantee that all allocators work that way. The obvious solution to >> me seems to be hardcoding the consistent DMA mask to 32-bit, but using >> 64-bit for regular dma mask if-and-only-if ADMA is enabled. > > That's not enough to fix the problem since there's issues with actual > transfer data being allocated above 4GB as well, not just the consistent > allocations (it appears that blk_queue_bounce_limit setting to 32-bit > doesn't prevent this on x86_64). Either we play some funky games with > changing the DMA mask of the entire device to 32-bit if either port is > in ATAPI mode (which blew up when I tried it) or we add the ability to > set the DMA mask independently on each port (like by setting the mask on > the SCSI device and using that for DMA mapping instead) which requires > core changes.
Its all funky games that no other driver is doing... There is one guaranteed to work scenario -- set all masks and bounce limits etc. to 32-bit. There is also one highly-likely-to-work scenario, disabling ADMA by default.
>> * it sure seems like there are other open sata_nv ADMA issues -- can >> we hard-confirm or deny this? bugzilla wasn't very helpful for me. >> It doesn't seem like we can disable ADMA (to solve those issues) and >> get enough test time in (which is what I said a week (or more?) ago >> too...) > > The NCQ/non-NCQ command switching issue is still hitting some people > (last I heard Kuan was looking into this), also there's a hotplug issue > that Tejun reported..
The former implies we need to disable swncq for 2.6.24, if it's not stable yet.
Jeff
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