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ExecutorElassus
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Joined: 11 Mar 2004
Posts: 758
Location: Stuttgart, Germany

PostPosted: Mon Feb 25, 2013 1:06 pm    Post subject: new install, grub2/grub.cfg manual, / on lvm Reply with quote

so, like it says: I'm installing gentoo new onto a laptop, and the root partition is on lvm (as in, on /dev/{vg}/{vg}-root), and I'm using grub2 with a manually written cfg file (because NeddySeagoon has a guide for an init script to run an initramfs, because /usr is also on lvm, but also because grub2-mkconfig persistently sets /usr as the root partition in its auto-generated cfg file). /boot is on /dev/md1 (raid1).

Thus:
How do I configure grub2 to load up the lvm partitions, so it can find the kernel?
How do I write up the grub2 config file?

Thanks,

EE
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tuner23
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Joined: 18 May 2006
Posts: 68

PostPosted: Wed Feb 27, 2013 9:26 am    Post subject: Reply with quote

Hy,

you can try doing this by creating an initramfs including a statically compiled lvm-version, like described here..
http://wiki.gentoo.org/wiki/DM-Crypt_LUKS

With busybox you can execute then lvm.

Best to configure is, when you make another grub-entry with an initram wich beams you to the shell after loading the kernel and before booting:
Code:
#!/bin/busybox sh

export PATH=/bin
umask 0077

mount -t proc none /proc
mount -t sysfs none /sys

echo "Mounting Rootfs"
#while [ ! -b /dev/mapper/rootfs ]
#do
#       cryptsetup luksOpen /dev/sda5 rootfs
#       sleep1
#done
#mount -r /dev/mapper/rootfs /rootfs
sh

umount /proc
umount /sys
exec switch_root /rootfs /sbin/init


But ist's hard stuff and if you are new, i would more prefer to ask: why?
My /root-partition is after several years already 314M
You can let the system boot and create a secondary partition for LVM including a usr, var and data partition, maybe also home if you put any stuff inside..


Greets,
Antonios.
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ExecutorElassus
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Joined: 11 Mar 2004
Posts: 758
Location: Stuttgart, Germany

PostPosted: Sat Mar 02, 2013 5:32 pm    Post subject: Reply with quote

okay fine then I'll do it the normal way. hmph.

Okay, now root's on /dev/md3, with the lvm on /dev/md4 like in the guide.

I have a manually-written grub.cfg file, and it now fails with the following:

Code:
error: /boot/kernel-3.8.1-gentoo not found
You need to load the kernel first


But that file exists, on /boot/ right where I specified in the file /boot/grub2/grub.cfg.

I used grub2-install to install grub to the mbr of both sda and sdb, but wrote grub.cfg manually rather than using grub2-mkconfig (since that method seems to be full of suffering and confusion).

Anyway, what's going wrong here?

Cheers,

EE
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popsUlfr
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Joined: 27 Feb 2011
Posts: 80

PostPosted: Sun Mar 03, 2013 1:57 pm    Post subject: Reply with quote

ExecutorElassus wrote:
okay fine then I'll do it the normal way. hmph.

Okay, now root's on /dev/md3, with the lvm on /dev/md4 like in the guide.

I have a manually-written grub.cfg file, and it now fails with the following:

Code:
error: /boot/kernel-3.8.1-gentoo not found
You need to load the kernel first


But that file exists, on /boot/ right where I specified in the file /boot/grub2/grub.cfg.

I used grub2-install to install grub to the mbr of both sda and sdb, but wrote grub.cfg manually rather than using grub2-mkconfig (since that method seems to be full of suffering and confusion).

Anyway, what's going wrong here?

Cheers,

EE


Why did you install grub 2 to two hard drives? You just place the one where grub 2 is installed into mbr as first boot device in your BIOS.
I just finished creating a Gentoo system on lvm with systemd,grub 2,uefi but for generating the initramfs I rather use mkinitcpio from Arch (it's in the portage) than genkernel for easy lvm2 support.
So I imagine you're working in chroot of your target system, for succesfull grub 2 installation you should have /dev, /sys and /proc mounted in it.
Code:

mount -t proc none /path/to/proc/in/your/chroot
mount -o bind /sys /path/to/sys/in/your/chroot
mount -o bind /dev  /path/to/dev/in/your/chroot


For grub 2 make sure you have the device-mapper useflag enabled and os-prober is installed.
Since your lvm logical volumes are already created do a
Code:

vgscan
vgchange -a y

To have them appear correctly in lsblk.

Now either use the lvm nodes in /dev/mapper or the UUID (you can get a ready for fstab string with 'lsblk -f -P -o UUID /dev/mapper/[yourlvmnode]') to add in your fstab.

Install grub 2 to the mbr of the disk of your choice
Code:
grub2-install /dev/sda


Then you generate the grub.cfg, you really don't want to do it by hand. Grub 2 will pick up everything automatically and load the needed modules if it resides on an lvm volume.
Code:

grub2-mkconfig -o /boot/grub2/grub.cfg


You need to make sure your initramfs has the adequate hooks for lvm2, but after that you should be good to go. Unmount all the stuff you mounted earlier and reboot.

The ArchWiki is great for more info on the LVM stuff.
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tuner23
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Joined: 18 May 2006
Posts: 68

PostPosted: Sun Mar 03, 2013 2:42 pm    Post subject: Reply with quote

Hy,


Is boot on an own partition?
Can you post the grub-configuration?

1. possibly the kernel can't read your filesystem (you have to compile your fs statically and not as module)
2. if boot is on an own partition, your kernel is
Quote:
kernel kernel-3.3.8-gentoo
, else it is
Quote:
kernel /boot/kernel-3.3.8-gentoo
.

Greets.
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ExecutorElassus
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Joined: 11 Mar 2004
Posts: 758
Location: Stuttgart, Germany

PostPosted: Mon Mar 04, 2013 5:03 pm    Post subject: Reply with quote

okay, to answer a few questions:

Quote:
Why did you install grub 2 to two hard drives?

For a number of reasons: the guide (though for grub[1]) says to, because I have /boot on a mirrored RAID array. I didn't want to muck around figuring out which of my drives is actually first in the BIOS boot list.

My initramfs is made from NeddySeagoon's handy guide. He also used a manual grub file. I've read some scarly-looking complaints about grub2 børking UUIDs and having messy config files, so I went with what I knew.

When I chroot into my (properly-mounted) environment, none of the mounts carry over. Is there a way to update mtab to match the actual mount situation?

EDITnvm that last bit. 'ln -sf /proc/mounts /etc/mtab' fixed it. Hope that wasn't a stupid thing to do :?

anyway, so now I told grub2-mkconfig to do it automatically. I'll report back in a sec to say if it worked.

Cheers,

EE
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ExecutorElassus
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Joined: 11 Mar 2004
Posts: 758
Location: Stuttgart, Germany

PostPosted: Mon Mar 04, 2013 5:13 pm    Post subject: Reply with quote

UPDATE: yeah, grub2-mkconfig totally didn't make a working config. It misidentified the root and /boot mduuids. How do I fix that? Do I have to go rewriting the files in /etc/grub.d/?

Cheers,

EE
PS- every stupid time I write out file names and commands, I keep hitting TAB for auto-completion. My browser hates me :(

Also, here is my grub.cfg written manually:

Code:
#
# This is a MANUALLY WRITTEN (holy shit!) grub-config, following NeddySeagoon's guide here:
# http://forums.gentoo.org/viewtopic-t-920644-highlight-.html
#
#


default 0
timeout 7
#splashimage=(hd0,0)/boot/grub/splash.xpm.gz


menuentry 'Gentoo' {
root=hd0,1
linux /boot/kernel-3.8.1-gentoo root=UUID=bb492953-3a45-47ed-9ef5-615147e13e78
initrd /boot/initrd.cpio.gz
}

menuentry 'Gentoo-prevkernel' {
root=hd0,1
linux /boot/kernel-3.8.1-gentoo root=UUID=bb492953-3a45-47ed-9ef5-615147e13e78
initrd /boot/initrd.cpio.gz
}


incidentally, the instruction to write simply "linux kernel-3.8.1-gentoo…" for the kernel line contradicts the grub2 guide and the gentoo documentation. Is that truly correct? /boot is, as I said, on a RAID1 array, as is /

cheers,

EE
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ExecutorElassus
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Joined: 11 Mar 2004
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Location: Stuttgart, Germany

PostPosted: Sun Mar 17, 2013 10:18 pm    Post subject: Reply with quote

okay, I've gotten a bit further with the config file. For this box, unlike my main, the kernel string has to be in the format 'kernel /kernel-3.8.x-gentoo' (or however I named it, but *with* a preceding slash) for the loader to find it. However, two things then happen:

the initrd does not get loaded, even when formatted the same, and the start process then hangs on a kernel panic. Or, more to the point, it hangs when it is unable to find the /init process.

So, this leads me to suspect that something is wrong with how I'm identifying the / partition (though the uuid is correct for /dev/md3), but also that something is wrong with how grub is loading partitions.

Any advice?

Cheers,

EE
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ExecutorElassus
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Joined: 11 Mar 2004
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Location: Stuttgart, Germany

PostPosted: Wed Mar 27, 2013 1:31 am    Post subject: Reply with quote

Sigh. I'm still having problems with this. I'm sure it's just something misconfigured: when I boot from the LiveCD, I can set up the md and lvm devices fine, and run from the root OS. But I can't boot the box on its own. Here's the present /boot/grub2/grub.cfg:

Code:
#
# This is a MANUALLY WRITTEN (holy shit!) grub-config, following NeddySeagoon's guide here:
# http://forums.gentoo.org/viewtopic-t-920644-highlight-.html
#
#


default 0
timeout 7
#splashimage=(hd0,0)/boot/grub/splash.xpm.gz


menuentry 'Gentoo' {
root=hd0,1
linux /kernel-3.8.1-gentoo root=UUID=bb492953-3a45-47ed-9ef5-615147e13e78
initrd /boot/initrd.cpio.gz
}

menuentry 'Gentoo-prevkernel' {
root=hd0,1
linux /kernel-3.8.1-gentoo root=UUID=bb492953-3a45-47ed-9ef5-615147e13e78
initrd /boot/initrd.cpio.gz
}

Here is the output of blkid:
Code:
# blkid
/dev/loop0: TYPE="squashfs"
/dev/sr0: LABEL="Gentoo Linux amd64 20130110" TYPE="iso9660"
/dev/sda1: UUID="5b60525c-e83a-7e01-cb20-1669f728008a" TYPE="linux_raid_member"
/dev/sda2: UUID="94e65518-6c42-46a8-99e7-c68aa531d574" TYPE="swap"
/dev/sda3: UUID="ed5d1009-5b52-bc94-cb20-1669f728008a" TYPE="linux_raid_member"
/dev/sda4: UUID="494b1b91-4220-4725-bb84-1e9ab089ffde" UUID_SUB="9822330e-20a0-d3c8-a328-e449a3f0a1ec" LABEL="livecd:4" TYPE="linux_raid_member"
/dev/sdb1: UUID="5b60525c-e83a-7e01-cb20-1669f728008a" TYPE="linux_raid_member"
/dev/sdb2: UUID="e5c374df-c0a7-4e79-9eea-80541ad71f9c" TYPE="swap"
/dev/sdb3: UUID="ed5d1009-5b52-bc94-cb20-1669f728008a" TYPE="linux_raid_member"
/dev/sdb4: UUID="494b1b91-4220-4725-bb84-1e9ab089ffde" UUID_SUB="60342ef3-ffbf-83ee-1b01-7c3ec3fdda25" LABEL="livecd:4" TYPE="linux_raid_member"
/dev/md1: UUID="f3751a22-b683-43b7-a74d-5d39ff7b117b" TYPE="ext2"
/dev/md3: UUID="bb492953-3a45-47ed-9ef5-615147e13e78" TYPE="ext3"
/dev/md4: UUID="vBcv7D-jQwi-14ft-cHah-pzol-c71h-m6eNaq" TYPE="LVM2_member"
/dev/mapper/choria-tmp: UUID="79d1bc8b-e7d3-41bb-b7e8-c4df1c574320" TYPE="ext2"
/dev/mapper/choria-var: UUID="6f70de91-3fa0-4989-a9cc-832568d38499" TYPE="ext3"
/dev/mapper/choria-usr: UUID="4079e7b4-9e84-4c92-863e-ebe4b152e38f" TYPE="ext3"
/dev/mapper/choria-usr--port--dist: UUID="168ad4fa-8c4c-415b-94be-8caf0ae41638" TYPE="ext2"
/dev/mapper/choria-usr--port: UUID="a4288177-9c30-4fec-a2b3-c4ee80b7812d" TYPE="ext2"
/dev/mapper/choria-home: UUID="8d842dea-8eda-45aa-af03-091f59345ebd" TYPE="ext3"
and here is the output of 'mdadm -E /dev/sda3' (one of the two partitions involved in the Raid1 array of / ):
Code:
# mdadm -E /dev/sda3
/dev/sda3:
          Magic : a92b4efc
        Version : 0.90.00
           UUID : ed5d1009:5b52bc94:cb201669:f728008a (local to host livecd)
  Creation Time : Mon Mar 18 12:14:32 2013
     Raid Level : raid1
  Used Dev Size : 6291392 (6.00 GiB 6.44 GB)
     Array Size : 6291392 (6.00 GiB 6.44 GB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 3

    Update Time : Wed Mar 27 02:22:35 2013
          State : clean
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0
       Checksum : 571c7417 - correct
         Events : 20


      Number   Major   Minor   RaidDevice State
this     0       8        3        0      active sync   /dev/sda3

   0     0       8        3        0      active sync   /dev/sda3
   1     1       8       19        1      active sync   /dev/sdb3

grub is built with device-mapper, and the config should be correct. But what am I missing here?

Cheers,

EE
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