Messages in this thread | | | Date | Mon, 15 Sep 2003 17:32:55 +0200 | From | Jens Axboe <> | Subject | Re: SII SATA request size limit |
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On Mon, Sep 15 2003, CASINO_E wrote: > Forgive me if I'm saying something stupid but, do you mean a special > case for this controller in ide-dma.c:ide_build_dmatable()?
No that's not stupid at all. In 2.4 that would be how you do it, in 2.6 I was referring to the possibility of letting the drive queues that hang off that controller be naturally limited. So you would do something ala
if (hwif->dma_boundary) blk_queue_segment_boundary(drive->queue, 0x1fff);
and then no segment would be >= 8192 (or cross it, naturally) by default.
> In this case, should not segment size and boundary be included in hwif > so we can have a generic ide_build_dmatable() without dealing > explicitly with special cases? We could initialize to the default for > most controllers and set the values for the exceptions inside each > particular driver.
Of course. But that is implementation detail, I was just worried that someone would clamp on a nasty work around like 15 sectors (which would in reality be just a 4kb request, nasty!) when you could get nice 128kb requests with just the right segment limiting instead.
But basically I don't understand why the work-around was _ever_ in sectors, if that is the bug in the hardware dma engine. Two explanations: it's not really that bug and NetBSD is wrong, or the person who did the work-around didn't know a better solution existed (don't laugh, I wouldn't be surprised if something like that came down from a vendor :)
-- Jens Axboe
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