initramfs-tools: does not activate logical volume - two obversations

[Martin Steigerwald]

Am Sonntag, 18. Januar 2015, 15:25:52 schrieb Ben Hutchings:
> Control: notfound -1 0.115~bpo70+1
> 
> On Mon, 23 Jun 2014 10:34:02 +0200 Martin Steigerwald <Martin at lichtvoll.de> 
wrote:
> > Hi!
> > 
> > I bzr diff on /boot/grub/grub.cfg revealed – but already from last week
> > as I upgraded to the newer backport initramfs-tools, where booting still
> > worked> 
> > okay:
> >  menuentry 'Debian GNU/Linux, mit Linux 3.2.0-4-686-pae' --class debian --
> > 
> > class gnu-linux --class gnu --class os {
> > 
> >         load_video
> >         insmod gzio
> > 
> > @@ -67,7 +90,7 @@
> > 
> >         set root='(hd0,msdos1)'
> >         search --no-floppy --fs-uuid --set=root [UUID]
> >         echo    'Linux 3.2.0-4-686-pae wird geladen …'
> > 
> > -       linux   /vmlinuz-3.2.0-4-686-pae
> > root=/dev/mapper/mondschein-debian ro +       linux  
> > /vmlinuz-3.2.0-4-686-pae root=UUID=[UUID ro
> > 
> >         echo    'Initiale Ramdisk wird geladen …'
> >         initrd  /initrd.img-3.2.0-4-686-pae
> >  
> >  }
> 
> [...]
> 
> The 'UUID=...' syntax is not supported for root on an LV.  You *must*
> use the /dev/mapper device name so that the lvm2 script can work out
> which VG to activate.  (It is not safe in general to activate all
> visible VGs.)

Its not me using a UUID, its update-grub. In /boot/grub/grub.cfg I have:

linux   /vmlinuz-3.16-0.bpo.3-686-pae root=UUID=[some UUID]

yet in /etc/fstab I have:

/dev/mondschein/debian  /  ext4    defaults                     0 1

In /etc/default/grub I do not set the root= parameter manually. In fact I 
have:

GRUB_CMDLINE_LINUX_DEFAULT=""
GRUB_CMDLINE_LINUX=""


So I do not see where I tell grub to use a UUID. For reference here is the 
complete grub configuration:

# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
#   info -f grub -n 'Simple configuration'

GRUB_DEFAULT=0
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT=""
GRUB_CMDLINE_LINUX=""

# Uncomment to enable BadRAM filtering, modify to suit your needs
# This works with Linux (no patch required) and with any kernel that obtains
# the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)
#GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"

# Uncomment to disable graphical terminal (grub-pc only)
#GRUB_TERMINAL=console

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
#GRUB_GFXMODE=640x480

# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux
#GRUB_DISABLE_LINUX_UUID=true

# Uncomment to disable generation of recovery mode menu entries
#GRUB_DISABLE_RECOVERY="true"

# Uncomment to get a beep at grub start
#GRUB_INIT_TUNE="480 440 1"



On Sid tough update-grub creates this:

root=/dev/mapper/sata-debian

which does seem to fit what you say initramfs-tools requires (except that by 
default it adds both devices to BTRFS RAID 1, see below about bug 747653).


Please re-open and if you really think its not initramfs-tools bug, reassign 
to grub-pc for having it use /dev/VG/LV syntax instead. Or advise on another 
solution. I can also keep the work-around of course, but its important to make 
sure that in Jessie this setup will work without any additional work-around. 
And if UUIDs are not supported for LVM, I think this deserves a promiment 
mention somewhere as well. Cause not booting due to not activing a logical 
volume is not so nice to the user.


This may be solved there with a patch similar to what upstream provided:

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=747653#25

I did not yet come around to build grub-pc myself into /usr/local and test 
this patch.

Ciao,
-- 
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
GPG: 03B0 0D6C 0040 0710 4AFA  B82F 991B EAAC A599 84C7
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