Re: [gentoo-user] Booting Gentoo from USB stick

[YoYo Siska]

On Wed, Sep 15, 2010 at 08:34:33AM +1000, Jake Moe wrote:
>  On 15/09/10 04:28, YoYo Siska wrote:
> >On Fri, Sep 10, 2010 at 07:29:01AM -0400, David Relson wrote:
> >>On Fri, 10 Sep 2010 11:05:12 +0200
> >>J. Roeleveld wrote:
> >>
> >>>On Friday 10 September 2010 10:43:30 Jake Moe wrote:
> >>>>   On 10/09/2010 5:27 PM, Maciej Grela wrote:
> >>>>>2010/9/10 Jake Moe<jakesaddress@×××××.com>:
> >>>>>>   Hello all,
> >>>>>>
> >>>>>>I've been thinking about creating a Gentoo USB stick for install
> >>>>>>and rescue purposes (and, of course, just to see if I could).
> >>>>>>I've mostly followed the Gentoo handbook (I used a single 4GB
> >>>>>>partition for the whole system, and no swap).  I've used
> >>>>>>genkernel for the kernel (so I can have a multi-system capable
> >>>>>>kernel).  I've gotten GRUB installed and working.  My problem
> >>>>>>comes in after what I believe is the init process:
> >>>>>>   * Checking root filesystem ...
> >>>>>>
> >>>>>>fsck.ext2: No such file or directory while trying to
> >>>>>>open /dev/sda1 /dev/sda1:
> >>>>>>The superblock could not be read or does not describe a correct
> >>>>>>ext2 filesystem.  If the device is valid and it really contains
> >>>>>>an ext2 filesystem (and not swap or ufs or something else), then
> >>>>>>the superblock
> >>>>>>
> >>>>>>is corrupt, and you might try running e2fsck with an alternate
> >>>superblock:
> >>>>>>     e2fsck -b 8193<device>
> >>>>>>
> >>>>>>   * Filesystem couldn't be
> >>>>>>fixed :( [
> >>>>>>
> >>>>>>!! ]
> >>>>>>Give root password for maintenance
> >>>>>>(or type Control-D to continue):
> >>>>>>
> >>>>>>
> >>>>>>If I give the root password, I can find no /dev/sda1.  However,
> >>>>>>mount shows /dev/sda1 on /, and there *is* a /sys/block/sda
> >>>>>>folders, with a sda1 folder in that as well.  It's almost like
> >>>>>>it had /dev/sda1, but then lost it somehow.
> >>>>>>
> >>>>>>Does anyone have any idea what's going on here?  Any help would
> >>>>>>be appreciated.
> >>>>>Have you seen http://www.sysresccd.org/Main_Page ? It's based on
> >>>>>Gentoo, you could check what they did to boot from a usb stick.
> >>>>>
> >>>>>Br,
> >>>>>Maciej Grela
> >>>>Excellent, thanks for that, I hadn't found it in my previous
> >>>>searches. I'll have a look there.
> >>>>
> >>>>Jake Moe
> >>>Had a similar issue a while ago when I was playing around with this
> >>>myself.
> >>>
> >>>Take a look at the linux boot parameters.
> >>>
> >>>The 'theoretical' part is: You need to let the kernel initialize the
> >>>USB-stick before trying to access it. (This can take some time)
> >>>
> >>>There is a delay-option, just can't remember the proper name off-hand.
> >>>
> >>>--
> >>>Joost
> >>I've got USB booting working in a syslinux environment.  A delay of 12
> >>seconds is working for me.  The syslinux.cfg stanza I use is:
> >>
> >>LABEL usb
> >>KERNEL linux
> >>APPEND rootdelay=12 root=/dev/sda2
> >The usual way for linux on removable usb sticks / disks is to use LABEL
> >or UUID to identify the disks and not the device names, because they
> >will be different in different computers ;) The downside is that you
> >need an initrd to mount the root partition... I think that the usual
> >initrd generated by genkernel works...
> >
> >If you created the rootfs with:
> >mkfs.ext2 -j -LUSBGentoo  /dev/sdXY
> >
> >then you can change the kernel parameter to
> >root=LABEL=USBGentoo
> >
> >and your fstab to:
> >LABEL=USBGentoo		/		ext3 ...
> >
> >You can also use the uuid of the filesystem, find it out with
> >dumpe2fs -h  /dev/sdb2 | grep UUID
> >and then use UUID=XXX instead of LABEL=XXX
> >
> >I never really played around with grub and  USB booting, so I use
> >syslinux. I create a small FAT partition with syslinux, kernel and
> >initrd image  (it gets also pretty handy when you sometimes need to copy
> >something from a windows machine ;) and a second "regular" ext3
> >partition for the rootfs.
> >
> >Basically you would do:
> >- partition the stick, mark the FAT partition as bootable/active
> >- format the partitions:
> >   - mkfs.vfat -nUSBData /dev/sdX1
> >   - mkfs.ext2 -j -LUSBGentoo /dev/sdX2
> >- install syslinux (on the FAT partition):
> >   - syslinux /dev/sdX1
> >- mount /dev/sdX2, install gentoo in the usual way
> >- compile the kernel and initrd, make sure required USB stuff is in the kernel
> >    (theoretically it could be as modules in initrd... but in-kernel is safer :)
> >   if you are in a hurry, or don't know how to create them, get them from
> >   a gentoo livecd ;) don't forget to also copy the modules
> >   (/lib/modules-XXX/...) from the livecd to the rootfs.
> >- put the kernel and initrd on the FAT partition (I name them  vmlinuz.img
> >   and initrd.img)
> >- edit syslinux.cfg (on the FAT partition), see
> >   http://syslinux.zytor.com/wiki/index.php/SYSLINUX#How_do_I_Configure_SYSLINUX.3F
> >   a very simple one from my USB disk:
> >
> >DEFAULT linux
> >LABEL linux
> >SAY Now booting USBGentoo
> >KERNEL vmlinuz.img
> >APPEND root=LABEL=USBGentoo initrd=initrd.img
> >
> >you might also add rootdelay=10 to the options if the usb stick/disk isn't
> >detected quick enough
> >
> >umount, reboot, set the computer to boot from usb, enjoy... ;)
> >Xorg without a config seems to work pretty well on most computers these
> >days, IIRC the alsa modules for soundcards are also autoloaded, so you
> >don't need any fancy hw detection to have a desktop running from USB
> >stick ;)
> >
> >
> >yoyo
> >
> >
> >
> >BTW there is also a "manual" way to boot even without an initrd: use
> >LABEL=XXX in your fstab, on the kernel command line use root=/dev/sda2
> >(or whatever you think will be more probable on you machines ;)
> >then try to boot it, if it is wrong, you can enter  the corrent
> >"root=/dev/sdX2" param in the syslinux prompt (you can either look up the
> >correct device in the boot messages, or just try sda, sdb, sdc, ... ;)
> >You could also create menu options for the usual cases... (sda...sdf
> >shoud be more than enough... ;)
> >You can however accidentally mount a rootfs from one of the disks on the
> >computer and thus booting the system on the computer, just with your
> >kernel...
> >
> >
> >
> >
> Thanks for that.  I originally tried with "LABEL=UsbRoot" in both
> GRUB and fstab, but it couldn't find it, so I put it in a system
> that I'd pulled the hard drive from, so I could test if it'd work
> with /dev/sda instead.  Neither method works; it just doesn't seem
> to see the USB storage in /dev.  When I try by label, I get what's
> in the attached error.
>
> I've had a quick look at SYSLINUX (and it's counterpart, EXTLINUX),
> and it appears to really be nothing more than another bootloader
> like LILO or GRUB.  Is that the case?  If so, I might try and
> overwrite GRUB with EXTLINUX and see if that works; it appears that
> it should be that easy.  Most of the USB booting doco I can find
> seems to want SYSLINUX anyway; maybe I'll give it a try.  I had
> thought that a USB storage device is storage like anything else, so
> a "standard" install should work.  Maybe it doesn't...

Yes, syslinux is just another "bootloader" ;) It his however
specifically created for removable disks. I don't know how exactly grub
works and how it handles "removable" disk (ie when the disk appears at
different places) when finding devices for its root partition and the
root option for kernel...

>
> Jake Moe

> >> Activiating mdev
> >> Determining root device...
> /init: line 477: blkid: not found\

seems like your initrd is missing the blkid program (used to determine
the labels and uuids of disks...)
Looking at the genkernel help it seems to ethis option:
        --disklabel             Include disk label and uuid support in your
                                ramdisk 

> !! Could not find the root block device in LABEL=UsbRoot.
>    Please specify another value or: press Enter for hte same, type "shell" for a
>  shell, or "q" to skip...
> root block device(LABEL=UsbRoot) :: /dev/sda1
> >> Mounting root...
> >> Booting (initramfs)..
> INIT: version 2.87 booting
>
> Gentoo Linux; http://www.gentoo.org/
>  Copyright 1999-2009 Gentoo Foundation; Distributed under teh GPLv2
>
> Press I to enter interactive boot mode
>
>  * Mounting proc at /proc ...                                             [ ok ]
>  * Mounting sysfs at /sys ...                                             [ ok ]
>  * Mounting /dev ...                                                      [ ok ]
>  * Starting udevd ...                                                     [ ok ]
>  * Populating /dev with existing devices through uevents ...              [ ok ]
>  * Waiting for uevents to be processed ...                                [ ok ]
>  * Mounting devpts at /dev/pts ...                                        [ ok ]
>  * Checking root filesystem ...
> fsck.ext2: Unable to resolve 'LABEL=UsbRoot'
This means fsck was unable to find the filesystem  with that label.
You can use dumpe2fs /dev/yourpartition to check if the filesystem
really has the cooret label (look for "Filesystem volume name" at the
top)

>  * Filesystem couldn't be fixed :(                                        [ !! ]
> Give root password for maintenance
> (or type Control-D to continue):

yoyo