I just remembered hdparm, and used it to turn DMA off on the dvd drive. The drive works fine that way. I conclude that there is a problem with use of UDMA(33) mode on this drive. I will file a bug. Steve Schwarz On Sun, 2006-05-21 at 17:33 -0700, Steven Schwarz wrote: > I recently became aware that there is something going wrong when I > mount data dvds on my fedora core 4 system. I became aware of this > using a data dvd rom that contains some software from Sun. I have > tested that the dvd is ok by using another system. The symptom is that > when I mount this dvd and try to compute checksums of files on it I > get a different random answer on each mount. There are no signs of > trouble as the system boots -- here is the relevant section > of /var/log/dmesg: > > ide: Assuming 33MHz system bus speed for PIO modes; override > with idebus=xx > ICH6: IDE controller at PCI slot 0000:00:1f.1 > ACPI: PCI Interrupt 0000:00:1f.1[A] -> GSI 18 (level, low) -> > IRQ 193 > ICH6: chipset revision 3 > ICH6: not 100% native mode: will probe irqs later > ide0: BM-DMA at 0xffa0-0xffa7, BIOS settings: hda:DMA, > hdb:DMA > Probing IDE interface ide0... > hda: HP DVD Writer 640b, ATAPI CD/DVD-ROM drive > hdb: ASUS CD-S480/AH, ATAPI CD/DVD-ROM drive > ide0 at 0x1f0-0x1f7,0x3f6 on irq 14 > Probing IDE interface ide1... > hda: ATAPI 40X DVD-ROM DVD-R CD-R/RW drive, 2048kB Cache, > UDMA(33) > Uniform CD-ROM driver Revision: 3.20 > hdb: ATAPI 48X CD-ROM drive, 128kB Cache, UDMA(33) > If it matters, the system is an hp pavilions desktop model a820n. > > As far as I can see, video dvds play fine on the same dvd drive. > > There are no messages produced to either dmesg or to /var/log/messages > when mounting or reading files from the dvd. > > I am running the latest fedora 4 kernel: kernel-smp-2.6.16-1.2108_FC4. > The problem also occurs with an older fedora 4 kernel: > kernel-smp-2.6.15-1.1833_FC4. > > Can anyone suggest anything I can do to work around this problem, or > to track down where it occurs? > > Thanks, > > Steve Schwarz >
