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<jakesaddr...@gmail.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:
Gentoo Linux; http://www.gentoo.org
Copyright 1999-2009 Gentoo Foundation; Distributed under the
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: 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...
Jake Moe
>> Activiating mdev
>> Determining root device...
/init: line 477: blkid: not found\
!! 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'
* Filesystem couldn't be fixed :( [ !! ]
Give root password for maintenance
(or type Control-D to continue):
