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I had a system booting over the network with PXE on 11.10. I upgrade to 12.04 and now the boot fails during startup with the following messsage:

Gave up waiting for root device. Common problems:

-Boot args (cat /proc/cmdline)
-Check rootdelay= (did the system wait long enough?)
-Check root= (did the system wait for the right device?)
-Missing modules (cat /proc/modules; ls /dev)
ALERT! /dev/nfs does not exist. Dropping to a shell!

My PXE config file is:

default linux

say Starting Legolas

LABEL linux
KERNEL legolas/vmlinuz
APPEND netboot=nfs root=/dev/nfs initrd=legolas/initrd.img nfsroot=,rsize=4096,wsize=4096 ip=dhcp pci=nomsi rw quiet

Any ideas why this does not work on 12.04? Thanks.

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up vote 3 down vote accepted

Correcting the pxeconfig line enabled the system:

APPEND boot=nfs root=/dev/nfs initrd=legolas/initrd.img nfsroot=,rsize=4096,wsize=4096 ip=dhcp pci=nomsi rw quiet

The change from above was only boot=nfs

I also want to point out that DisklessUbuntuHowto does not mention the boot=nfs parameter, and I could not get the system to boot without it. I hope someone with the same issues finds this before they waste too much time.

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Are you sure this was the issue? I'm booting 12.04 from PXE fine without boot=nfs. My line: APPEND root=/dev/nfs nfsroot= initrd=ubuntu/12.04/initrd.img-3.5.0-19-generic ip=dhcp rw -- (removed hardware specific workarounds unrelated to PXE). Maybe the unneeded (or even wrong?) netboot parameter was causing it instead. – gertvdijk Jan 16 '13 at 16:12

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