On Fri, Sep 27, 2002 at 07:03:49PM +0200, Hanspeter Roth wrote:
> Hello,
> 
> I intend to run cdrecord concurrently on multiple cdwriters.
> Dmesg seems to report that the drive has DMA mode 2 and Ultra-DMA
> mode 2 (Ultra/33).
> 
> cd1 at atapibus1 drive 0: <PLEXTOR CD-R   PX-W4012A, 563001, 1.02> type 5 cdrom removable
> cd1: 32-bit data port
> cd1: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 2 (Ultra/33)
> cd1(pciide1:0:0): using PIO mode 4, Ultra-DMA mode 2 (Ultra/33) (using DMA data transfers)
> 
> Nevertheless when burning by cdrecord (1.10) on a single drive the
> CPU is already loaded to much. It seems to me that DMA is turned off.
> 
> How can one control the data transfer mode of Atapi drives?

With flags in the kernel config file. See wdc(4), wd(4) and cd(4).
But if the kernel say it's using Ultra-DMA mode 2 at boot time, and
doesn't say anything else later, then it's really using Ultra-DMA mode 2.

-- 
Manuel Bouyer <bouyer@antioche.eu.org>
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