(Please check that the problem happens on Linus' tree if not then file under the Alternate Trees category.) Exact Kernel version:Current Linus' Bitkeeper tree Distribution: Gentoo Hardware Environment: Dell Dimension Pentium 3 Software Environment: gcc-2.95.3 Problem Description: Steps to reproduce: If the kernel is configured with: CONFIG_UNIX98_PTYS = N CONFIG_DEVFS_FS = Y CONFIG_DEVFS_MOUNT = Y at boot a kernel panic occurs with this msg: VFS: Cannot open root device "hda2" or 03:02 Please append a correct "root=" boot option Kernel panic: VFS: Unable to mount root fs on 03:02 But if I compile with CONFIG_UNIX98_PTYS = Y CONFIG_DEVFS_FS = Y CONFIG_DEVFS_MOUNT = Y the kernel boots.
Created attachment 33 [details] Kernel configuration: unable to mount root with DEVFS compiled in
Same problem here with a _heavy_ patched kernel version 2.5.49. But in my setup the kernel is unable to mount root even with CONFIG_UNIX98_PTYS=y. Tried two kernel configurations only differing in CONFIG_DEVFS_FS being set or unset, and I get the following: # CONFIG_DEVFS_FS is not set => kernel boots OK CONFIG_DEVFS_FS=y => kernel panics trying to mount root # CONFIG_DEVFS_MOUNT is not set # CONFIG_DEVFS_DEBUG is not set The differences in the kernel configuration files are as follows: --- /tmp/config-KO 2002-11-27 00:09:31.000000000 +0100 +++ /tmp/config-OK 2002-11-26 23:55:00.000000000 +0100 @@ -816,9 +816,7 @@ # CONFIG_NTFS_RW is not set # CONFIG_HPFS_FS is not set CONFIG_PROC_FS=y -CONFIG_DEVFS_FS=y -# CONFIG_DEVFS_MOUNT is not set -# CONFIG_DEVFS_DEBUG is not set +# CONFIG_DEVFS_FS is not set CONFIG_DEVPTS_FS=y # CONFIG_QNX4FS_FS is not set # CONFIG_ROMFS_FS is not set I am about to create an attachment with the kernel config that fails to mount root, just for reference. If there is interest to repeat the test with unpatched kernel sources, I will do.
Read http://www.lkml.org/archive/2002/12/13/50/index.html Does that fix your problem too ?
Sorry for the one month long delay :-(. I have just tried the same configuration with kernel versions 2.5.54 and 2.5.55 (devfs compiled in, but not automatically mounted at boot). 2.5.55 boots ok with no workarounds needed, but 2.5.54 fails to mount root. Applying the "LILO append trick" in the URL Dave posted doesn't help, though I didn't try to remove the four lines of code and recompile.