Bug#588675: Narrowing on location of bug #588675
reassign 588675 linux-source 2.6.32
retitle 588675 SCSI subsystem forgets root device on boot
found 588675 2.6.18
found 588675 3.2.63-2
submitter 588675 !
quit
I suspect the list of kernel versions with this bug is rather longer, but
I'm merely including some of those I'm certain it does effect. I suspect
even the latest kernels are effected, but I haven't confirmed this.
Thankfully I finally noticed an ingredient crucial enough to narrow down
the list of causes to a reasonable length.
The bug's manifestation is fairly simple, on an effected system:
$ head -2 /proc/mounts
rootfs / rootfs rw 0 0
/dev/root / ext3 ro,errors=continue 0 0
$
Whereas on an uneffected system:
$ head -2 /proc/mounts
rootfs / rootfs rw 0 0
/dev/sda1 / ext3 rw,errors=continue 0 0
$
And another uneffected example:
$ head -2 /proc/mounts
rootfs / rootfs rw 0 0
/dev/mtdblock2 / jffs2 rw,relatime 0 0
$
The two crucial ingredients for reproducing this bug, the system must
boot directly onto the root device (no initrd) and the root device must
be something that plugs into the SCSI subsystem.
This effects x86, PowerPC, MIPSel and likely other machines. This
effects systems with SATA main disks (SATA devices go through the SCSI
subsystem) as well as root on USB devices (yes, it *is* possible to get a
kernel to directly boot onto a USB key).
This does NOT effect older kernels when booting onto IDE subsystem disks
(/dev/hd* with newer kernels IDE disks go through the SCSI subsystem and
are likely effected). This does not effect systems which initially mount
*any* other device as root, and subsequently chroot onto a SCSI subsystem
device (this explains why initrd system are uneffected).
While this bug is mostly harmless, it is the root cause behind bugs
620465, 653073, 656333, and may very well have caused other bug reports
I'm unaware of.
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