Red Hat Bugzilla – Bug 58027
[ide-scsi] Linux hangs when trying to mount the cdrom
Last modified: 2007-04-18 12:38:53 EDT
Description of Problem:
When i try to mount the cdrom, the system hangs and requires a hard
Version-Release number of selected component (if applicable):
red hat linux
Steps to Reproduce:
I have installed redhat liux 7.2 under intel where i am facing the problem of
system freezing when trying to mount the cdrom (iso ).
I have also installed redhat linxu 7.1 under amd which isworking proper
do you have any idea which model cdrom you're using ?
(if not, typing
as root will tell me which it is)
I have come across the same problem on:
1, linux 7.2
2, An AMD k63
3, CD re-write drive, a Goldstar/LG, GCE-8160B., ide channel 1, set as master
with a slave SYQUEST drive.
When I try to mount a disk for read, the read light flashes for about 30 seconds
and then a re-boot is required. The same thing happens if I do a dd
The cd-rom was set up to be used for re burning with cdrecord, i.e. ide-scsi was
I have now removed the ide-scsi and access the CD-rom directly on hdc and I can
now use the cd-rom for read only, which is only OK for the short term.
I saw that round about release 2.4.10 of the kernel, a bug was fixed for scsi
buffer race condition, any comment on that patch as a possible fix?
This will only help if you are using the SCSI emulation.
You can tell by see which real device /dev/cdrom is linked to, if it is linked
to something like /dev/sc0, then you have scsi emulation.
To get the full picture, see /usr/share/doc/howto/CDROM-howto, if you have that
The way I disabled ide-scsi is as follow:
I am using grub as the boot loader.
I have a boot file system called /boot
go into /boot/grub/grub.conf and remove the words "hdc=ide-scsi", your cd-rom
may not be hdc, you will need to sort that. Then re-boot. Don't forget to save
a copy of your old config file in case everything goes pear shape.
Hope that works for you, best of luck.
My final comment on this one:
In my case, the problem was caused by the the fact that when using the ide-sccsi
driver, the mode of access default to DMA. Once I have disabled dma access,
every thing now works.
I have to disable DMA by changing /etc/rc.d/ec.local, I added the line:
hdparm -d0 /dev/hdc