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cyril 04-08-2004 06:10 AM

Trying to understand how a boot loader handles initrd/initramfs/ramdisk ...
 
Hi all,

I'm currently porting linux to a proprietary board, ARM based, which
already runs a -again- proprietayre monitor. Under this monitor,
to avoid re-doing everything, i've also written a linux boot loader,
which starts to work.

My machine is diskless, screen less, ... only a serial line for the moment.
I'm using kernel 2.6.4, cross-compiled on an intel linux box.

I encounter a few troubles with initrd and related stuff .

What i want to do is create my own file system (root) and make a ramdisk
with it, and use it right after booting with no other operation.

I've the gzipped ext2 image of this directory/file tree flashed on my board,
so i though it would be a good candidate to give it as an initrd image,
but i do not succeed yet to make it work and do not understand a few things :
  • I've setup a TAG list with an ATAG_INITRD2 for the initrd, but i don't know
    if this should point to a compressed or uncompressed ext2 image ?
  • I do not understand if the ATAG_RAMDISK tag is related to the
    initrd stuff, or another ramdisk issue ?
  • When i boot, i got :

checking if image is initramfs...it isn't (ungzip failed); looks like an initrd

But i don't even now what an initramfs is !? :confused:

Seems to be a new stuff in 2.6 kernel, but where is there a documentation on that ?
  • Last, for now, what "root=..." command should i pass to the kernel ?


Thanks for any help, doc , links on these


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