Re: /dev/fd0 causes Kernel PANIC, stalled system, permanent D-wait

Theodore Y. Ts'o (tytso@MIT.EDU)
Wed, 9 Apr 1997 17:52:39 -0400

Date: Wed, 09 Apr 1997 00:35:45 -0500
From: "Dan St.Andre'" <>

I wrote the following after a brief thread on about use of /dev/fd0 causing various system
faults. We are still running the RedHat 3.0.3 kit with the v1.x
kernel and drivers shipped with RH 3.0.3. I've read the fd0 driver
code (whew its old and dusty according to the remarks) and it looks
okay at that level. That makes me suspect an interaction between the
FS and FD0. We see no troubles on HDA with ext2 file systems.

My guess is that it's a hardware problem with your floppy drive...

QUESTION: Is there klog output we can easily enable to watch for low level
I/O errors from the diskette? To see why we enter D-wait ... and
just stay there?

Change klogd so that it starts up with a "-c 7" option. That will echo
all console logging messages to the console, which might give you some
useful information.

BTW. It must be a default but all of our ext2 diskettes show
"errors=continue" as the default according to tune2fs. Could it be
that mount is not respecting the superblock on diskettes? [I could
not get automatic fsck, after time or mount events, to work so I'm

The "errors=continue" means that after certain filesystem format
inconsistencies are found, the kernel will continue instead of panicking
or remounting the filesystem read/only (your two other choices). But
that won't protect you against certain low-level hardware faults which
cause the floppy disk drive to lock up or to retry the read forever....

- Ted