Re: [gentoo-catalyst] Re: minimal install on usb key

[Zac Medico]

Christophe PEREZ wrote:
> Le Thu, 23 Jun 2005 09:14:07 -0400, Chris Gianelloni a écrit :
>
>
>>Copy the contents of the CD to the USB key and it'll boot.  You just
>>have to use cdroot=/dev/sda1 (or wherever your key is).
>
>
> Ok, I've got it now.
> But I had to search a lot.
> First, I had of course to put a grub on the usb key.
> Then, to had a rootdelay= option for the boot wait to my usb key.
> But, it was no sufficient because, I don't know why, but udev doesn't
> create /dev/sda and /dev/sda1
> (runUdev in /linuxrc)
>
> (something strange, udevstart which is in /bin is called by
> /sbin/udevstart in /etc/initrd.scripts but modifying it never change for
> /dev/sdaX)
>
> I had to add :
>         ################### FOR USB BOOT ###################################
>         echo -e "${WARN}>>${NORMAL}${BOLD} We must hard create device nodes"
>         /usr/bin/mknod /newroot/dev/sda b 8 0
>         /usr/bin/mknod /newroot/dev/sda1 b 8 1
>         ################### END FOR USB BOOT ###############################
>
> before bootstrapCD in /linuxrc
>
> Now it works, but no really so simple as just copying files from iso to
> usb key.
> I'll put that img on my site soon if somebody is interested...
>

The rootdelay parameter should work (use a 5 or 10 second delay) with root=/dev/sda1 (no initrd) and statically linked usb drivers.  If the usb drivers are modular then you need to have a delay inside linuxrc between the modules loading and udevstart (again, sleep 5 or 10 should do it).  A parameter like "scandelay" is useful for tuning this. 

Note that if you get the 'Please specify a device to boot, or "shell" for a shell...' message then you can choose shell, run udevstart, exit, and try to specify your root device again.  There is a loop there inside linuxrc that helps for troubleshooting.  You should see your block device inside /sys/block if it has been detected properly.

Zac
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