[syslinux] centos and extlinux

[H. Peter Anvin]

Jerry Geis wrote:
> I am trying to use extlinux on centos 5.2 i386 to boot a thumbdrive.
> 
> I ran the commands:
> mkdir -p /boot/extlinux
> extlinux /boot/extlinux
> cat /usr/lib/syslinux/mbr.bin > /dev/sde
> cp /boot/vmlinux.latest.kernel /boot/extlinux/linux
> 
> I then tried to boot the USB stick and it started booting
> but then it says:
> 
> kernel panic unknown root device.
> 
> What else do I have to do. I followed the instructions in 
> /usr/share/doc/syslinux/extlinux.doc
> 

You successfully booted the kernel, however, the kernel has no idea 
where to mount the root filesystem.

Furthermore, most distribution kernels also need an initial ramdisk 
(/boot/initrd*).  All in all, you need a configuration file 
(extlinux.conf) which probably needs to look something like:

label linux
	kernel vmlinuz-blah
	append initrd=initrd-blah.img ro root=something

where "something" is a description of your root device, like a device 
name, a LABEL or a UUID.

	-hpa