Re: Problems with scsi emulation

[Douglas Gilbert]

 > I'm using a customized 2.4.20 kernel (red hat 9) with
 > scsi emulation, scsi  cdrom & scsi generic support
 > options enabled in .config and hdx-ide-scsi in
 > lilo.conf. apps as cdrecord or cdrdao take up all my
 > cpu time (I have a duron 1.1 gz, kt133, 192mb sdram,
 > 30 gb 5400 rpm hd). in windows (with dma enabled) Nero d
 > oesn't take up any (or almost) cpu time...
 > is this an issue of the linux-kernel or a configuration
 > problem?

Due to many problems with DMA locking up on ATAPI writers
earlier in the lk 2.4 series, Linux takes a very
conservative approach and turns off DMA.
It can be turned back on with:
  # hdparm -d 1 /dev/hdb
assuming your cdwriter is found at /dev/hdb (even
though the ide-scsi driver "owns" that device
and you address it as /dev/scd0 ). You can get
faster DMA modes with the addition of the "-X"
switch in hdparm but that should not be necessary.

Doug Gilbert