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Re: using bootcd with usb cdrw drive



On Wed, Oct 24, 2001 at 10:31:21PM +0200, Debian User Jean-Baptiste Note wrote:
> Well, i'm sorry i'm really not an expert, but maybe you should
> try a kernel with a initrd option.
> With a initrd, you'll get somewhat of a prompt and the ability
> to modprobe any module you like, it could help you to debug
> your problem.

Actually, after some rather extensive web search, I found out that
generally one cannot load USB devices as root from the kernel without
additional trickery.  The problem is that the usb devices are detected
asynchronously, so there is a race as to whether they are detected before
the root filesystem is mounted, a race which on my computer they always
lose.  So the trick will be to introduce some sort of delay before mounting
the root filesystem.  I believe one could do this with an initrd as you
suggest (either putting a delay script or just waiting at the prompt
manually).  

The approach I've taken is adding an additional delay into the kernel
(copying and modifying some code I found to do the same for a USB floppy).
Now for some reason my USB CDRW has stopped being able to write (which is
very annoying!), so I haven't been able to test it.  Actually, I just
realized that I could test it by loading the kernel off the hard drive but
specifying the CD as the root FS by root=/dev/scd0, but of course the whole
point is to be able to make a bootable CD (which requires writing).  :(

As per your suggestions, I have been using a monolithic kernel (no
modules), and I tried for a while to make one with an initrd, but was
confused, and unable to write a CD anyways.  It's so annoying! It started
out not working and then worked, and then stopped again.  Oh well.

Thanks for your help!

David.


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