Re: 2.1.111: IDE DMA disabled?

Linus Torvalds (
25 Jul 1998 18:53:41 GMT

In article <>,
John Hayward-Warburton <> wrote:
>Saw in drivers/block/ that IDE DMA code was buggy and had
>not been enabled in 2.1.111. I must confess to having seen no
>problems on this machine (can't remember whether it's HX or TX
>Intel chipset), Quantum Fireball SE 8.4A using Ultra-DMA on /dev/hdc
>and an older Seagate ST32140A on /dev/hda, Intel P233MMX, Gigabyte
>GA-586TX2 m/b, no SCSI anywhere.
>Was this intentional? hacked here to enable DMA again.

It was very much intentional.

People claim that the DMA problems may be due to having IDE cables of
bad quality or too long for the spec. HOWEVER, that claim misses the
point: even if the cable is bad it's not ok to have silent corruption,
so there is something wrong with the driver with DMA enabled. The newer
IDE standards are supposed to have CRC checks, and obviously they aren't
triggering for some reason.

This I disabled DMA until somebody can tell me what is up, rather than
just suggest people try shorter cables.


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