Chances are that at some time, you’ll need to repair a corrupted filesystem, or worse, fix something you accidentally broke. Sometimes, your operating system will do this, especially if you are a fan of Linux. Such as the case with the Core2, today:
[ 0.179209] Unpacking initramfs... [ 1.176420] ------------[ cut here ]------------ [ 1.176514] WARNING: at arch/x86/mm/init.c:504 free_init_pages+0x53/0x11f() [...] [ 1.177589] Call Trace: [ 1.177672] [<ffffffff81734b42>] dump_stack+0x19/0x1f [ 1.177759] [<ffffffff8104d6b6>] warn_slowpath_common+0x62/0x7b [ 1.177846] [<ffffffff8104d6e4>] warn_slowpath_null+0x15/0x17 [ 1.177933] [<ffffffff81037181>] free_init_pages+05x3/0x11f [ 1.178025] [<ffffffff81d32c4b>] free_initrd_mem+0x30/0x35 [ 1.178112] [<ffffffff81d1db2b>] populate_rootfs+0xeb/0x10c [ 1.178199] [<ffffffff81d1da40>] ? unpack_to_rootfs+0x289/0x289 [ 1.178286] [<ffffffff8100209b>] do_one_initcall+0x9b/0x135 [ 1.178373] [<ffffffff81d1b8eb>] kernel_init_freeable+0x154/0x1ea [ 1.178461] [<ffffffff81d1b981>] ? kernel_init_freeable+0x1ea/0x1ea [ 1.178550] [<ffffffff81725900>] ? rest_init+0x74/0x74 [ 1.178636] [<ffffffff81725909>] kernel_init+0x9/0xd6 [ 1.178723] [<ffffffff8173d73c>] ret_from_fork+0x7c/0xb0 [ 1.178810] [<ffffffff81725900>] ? rest_init+0x74/0x74 [ 1.178900] ---[ end trace ded000897d630586 ]--- [ 1.179052] Freeing initrd memory: 11812k freed
Long story short, the kernel became unhappy with the latest update, and being a headless machine with no remote hands, I had to figure how to fix it.
Now, although I don’t have remote hands, I have a fairly dated (and limited) sysrescue image which I can boot the system from, and manipulate my installation from there.
Despite architectural and distribution differences, a 3.x kernel with most options available can get you back online with minimal effort.
Althought teaching you how to handle LVM/etc is not something for a quick little diary entry, I will offer this bit of advice: The following mounting heirarchy tends to work OK for Debian, CentOS, and almost any other Linux distribution I’ve thrown at it:
# fsck.{filesystem} /dev/{device}{partition} #root partition
# mount -t {filesystem} /dev/{device}{partition} /mnt
# mount -o bind /dev /mnt/dev
# mount -t sysfs sys /mnt/sys
# mount -t devpts pts /mnt/dev/pts
# mount -t proc proc /mnt/proc
# cd /mnt
# {mount/fsck any subpartitions here}
# chroot /mnt /bin/{dash|bash|ash}
Happy repairs!