[ltp] 770ED and Dock SCSI vs hdparm DMA

James Hawtin linux-thinkpad@www.bm-soft.com
Thu, 30 Nov 2000 11:16:51 +0000 (GMT)

Thats quite an old model... are the IDE drives on the a PCI or IDE bus?
and how much ram have you got?

There is a problem with DMA on IDE buses in that DMA cannot address more
than the first 16Meg of memory. if you have an IDE bus based system and
more than 16Meg of ram you may be runnign into this problem, the problem
is DMA buffers can be allocated and deallocated on the fly however due to
the linear memory model of linux it might not be possible to get space in
the 0-16Meg area.

However these is a way to tune it so the buffer is allocated at the
begging and never removed... But I ahve forgotted how to do this off hand.


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