Re: DMA and my Maxtor drive

From: Jeff V. Merkey (jmerkey@timpanogas.org)
Date: Fri Oct 20 2000 - 17:36:35 EST


Linux 2.X trees are tested with memory sent from the buffer cache to the
disk I/O subsystem aligned on 512-byte boundries. This error is
typically seen is someone is passing memory via calls to ll_rw_blk()
that are not at a minimum 512-byte aligned, which can result in a wrap
case that will hang the IDE DMA controller. Linux I do not believe has
been tested with any other alignment. When I first saw these errors
when I was writing my own LRU for the NWFS file system, alignment was
the cause.

:-)

Jeff

linux@cr753963-a.glph1.on.wave.home.com wrote:
>
> I get this when DMA is enabled:
>
> Oct 20 15:39:07 cr753963-a kernel: hdb: timeout waiting for DMA
> Oct 20 15:39:07 cr753963-a kernel: hdb: irq timeout: status=0x6e {
> DriveReady DeviceFault DataRequest CorrectedError Index }
> ide0: reset: success
> Oct 20 15:39:07 cr753963-a kernel: hdb: DMA disabled
> Oct 20 15:39:07 cr753963-a kernel: ide0: reset: success
>
> It only happens when there lots of data is being transferred, or compiled
> on the drive.. The drive status is this:
>
> /dev/hdb:
>
> Model=Maxtor 82560A4, FwRev=AA8Z2726, SerialNo=C40LTQGA
> Config={ Fixed }
> RawCHS=4962/16/63, TrkSize=0, SectSize=0, ECCbytes=20
> BuffType=DualPortCache, BuffSize=256kB, MaxMultSect=16, MultSect=off
> CurCHS=4962/16/63, CurSects=5001696, LBA=yes, LBAsects=5001728
> IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
> PIO modes: pio0 pio1 pio2 pio3 pio4
> DMA modes: mdma0 mdma1 *mdma2
>
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