[SOLVED]How to boot from a mobile disk?

who is Jackson · n00b Joined: 10 Feb 2012 Posts: 19

I tried to follow the official handbook to install gentoo in my mobile disk ,but it always failed to bootloaded, sometimes it would go into black screen,and sometimes it would cause kernel panic .I suspected that there were something wrong with my kernel configuration . But in fact ,the configuration worked in the vmplayer~Anyone would like give me a hand?

smartass · Posted: Mon Feb 20, 2012 5:06 pm Post subject:

A common mistake is to try to boot from a partition with filesystem X, while the module for the X filesystem is on that partition. Your partition setup would shed some light on your situation.

If you're bootin with grub 0.97, make sure it's a filesystem that it won't choke on.

NeddySeagoon · Posted: Mon Feb 20, 2012 7:32 pm Post subject:

who is Jackson,

The hardware driver for your mobile disk USB?
must be built into the kernel.

Further, the kernel tries to mount root before it initalises the USB subsystem. This is a very bad thing if your root filesystem is on USB.
Add rootdelay=7 to your kernel line in grub.conf. This makes the kernel wait for 7 seconds before attempting to mount root, in this time the USB subsystem has been started.

Play with numbers if you wish to discover what works for you.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

who is Jackson · n00b Joined: 10 Feb 2012 Posts: 19

Thanks all!I will have a try tonight~

who is Jackson · n00b Joined: 10 Feb 2012 Posts: 19

I fixed this problem by using "genkernel --no-clean --no-mrproper --disklabel ramdisk",and then added a line in the grub.conf like this :"initrd /boot/initramfs-genkernel-x86_64-3.2.1-gentoo-r2"~~

rootor · n00b Joined: 05 Dec 2011 Posts: 25

I also want to have a try ...

who is Jackson · n00b Joined: 10 Feb 2012 Posts: 19

rootor:
Good luck!

NeddySeagoon · Posted: Sun Feb 26, 2012 6:30 pm Post subject:

rootor,

genkernel is more usually a part of the problem than the solution.

Make your kernel the normal way but ensure that SCSI Disk, USB Storage and your USB chip set drivers are built into the kernel. Modules cannot work.
In your grub.conf add rootdelay=y to the kernel line.

Installing grub on USB media so you can boot from it later can be a challenge because the USB device mayl become /dev/sda when its used for booting but it won't be there when you need to install grub.
You won't know if this happens to you until you try
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

who is Jackson · n00b Joined: 10 Feb 2012 Posts: 19

NeddySeagoon
rootdelay=7 didn't work on my laptop,and it would course kernel panic without "initrd /boot/initramfs-!initrd-XXX "!

NeddySeagoon · Posted: Sun Mar 11, 2012 8:57 pm Post subject:

who is Jackson,

If you want to use an initrd, I don't know how you boot from USB. The problem is that the rootdelay=7 is swallowed up by delaying the mount of the initrd and it needs to be appled to real_root.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

who is Jackson · n00b Joined: 10 Feb 2012 Posts: 19

Here is my grub.conf: