Apologies for the length of this post. A little while ago somebody
recommended my setting the DVD/CDROM for DMA operation to eliminate
jerkiness when viewing DVDs. I got hold of hdparm and tried it out,
without much apparent success. Does the following mean that DMA is
already enabled for the drive?
[root@localhost lcl]# /sbin/hdparm -i /dev/hdd
/dev/hdd:
Model=IDE DVD-ROM 16X, FwRev=V3.10, SerialNo=
Config={ Fixed Removeable DTR<=5Mbs DTR>10Mbs nonMagnetic }
RawCHS=0/0/0, TrkSize=0, SectSize=0, ECCbytes=0
BuffType=unknown, BuffSize=0kB, MaxMultSect=0
(maybe): CurCHS=0/0/0, CurSects=0, LBA=yes, LBAsects=0
IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
PIO modes: pio0 pio1 pio2 pio3 pio4
DMA modes: sdma0 sdma1 sdma2 mdma0 mdma1 mdma2 udma0 udma1 *udma2
AdvancedPM=no
[root@localhost lcl]# /sbin/hdparm -X66 -d1 /dev/hdd
/dev/hdd:
setting using_dma to 1 (on)
HDIO_SET_DMA failed: Operation not permitted
setting xfermode to 66 (UltraDMA mode2)
Segmentation fault
[root@localhost lcl]# /sbin/hdparm -X66 -d0 /dev/hdd
/dev/hdd:
setting using_dma to 0 (off)
HDIO_SET_DMA failed: Operation not permitted
setting xfermode to 66 (UltraDMA mode2)
Segmentation fault
But:
[root@localhost lcl]# /sbin/hdparm -X12 -d0 /dev/hdd
/dev/hdd:
setting using_dma to 0 (off)
HDIO_SET_DMA failed: Operation not permitted
setting xfermode to 12 (PIO flow control mode4)
using_dma = 0 (off)
No segfault with the following but no success either.
[root@localhost hdd]# /sbin/hdparm -d1 /dev/hdd
/dev/hdd:
setting using_dma to 1 (on)
HDIO_SET_DMA failed: Operation not permitted
using_dma = 0 (off)
cat /proc/ide/ide1/hdd/settings confirms that DMA is disabled.
This is all very confusing. So how to get rid of the jerkiness? This
is a 1.8 GHz Athlon XP 2200+ with the nVidia driver for Mandrake 8.2,
and 512 Mb RAM. The jerkiness was unaffected by installation of the
new video driver. On the old machine, 500 MHz Pentium III with 256 Mb
RAM the disk plays perfectly smoothly, but in that case DMA is enabled,
by default.
Could this be a hardware problem, like a jumper setting? No manual for
the drive. The invoice describes it as a "16X generic DVD drive".
--
Len Lawrence
----------------------------------------------------------
Everywhere I go I'm asked if I think the university stifles writers. My
opinion is that they don't stifle enough of them. There's many a bestseller
that could have been prevented by a good teacher.
-- Flannery O'Connor
----------------------------------------------------------
Want to buy your Pack or Services from MandrakeSoft?
Go to http://www.mandrakestore.com
