ramdisk pb

Richard Lightman richard at nezumi.plus.com
Fri Oct 25 00:33:10 PDT 2002

* Sébastien Person <sebastien.person at insa-rouen.fr> [2002-10-25 06:39]:
> Hi,
> I've setup a working lfs. And then tried to make a cd as described in
> Easy boot C of your LFS (3.3) doc found in lfs hints.
> My CD begin to boot but it hangs suddently :
> VFS cannot open root device "ram0" or 01:00 ...
> so I reboot to the lfs install (on HD) and tried to do :
> dev_ram=/dev/ram0
> mke2fs -m 0 $dev_ram
> but it doesn't want and say :
> can't locate module block-major-1 
> So I didn't know what does that mean ? Does it mean that ramdisk isn't
> supported ? or does it mean that he needs a special module ?
Linux cannot boot with a root device that requires a module.

You can use ramdisks by adding:
alias block-major-1 name_of_the_ramdisk_module
to /etc/modules, and running modprobe. There is no point to this. Use
tmpfs instead.

To boot from a ramdisk, support for it must be compiled into the
kernel. You can then use the ram disk image to load modules and change
to a root device that reqires modules.

The only reason I can think of for doing this with a CD is to support
booting from cd attached to an unknown SCSI card. Some combinations
of SCSI cards cannot be compiled into the kernel at the same time,
so you have to load the correct module from a ram disk.

If you are not doing this, compile the cdrom driver and iso9660 into
the kernel, and boot with the cd as your root device.


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