Custom initrd using busybox

[Rob Landley]

On Sunday 05 November 2006 6:34 pm, Luciano Miguel Ferreira Rocha wrote:
> On Sun, Nov 05, 2006 at 03:19:40PM -0500, Rob Landley wrote:
> > > - Documentation/filesystems/ramfs-rootfs-initramfs.txt
> > 
> > I wrote that one.  If it's missing something, let me know.
> 
> Information about the rdinit parameter would be nice. :)

I think the current version (2.6.18 and up) mentions it?

> It is in kernel-parameters.txt but I never searched for such an option.
> 
> Also, it reads "The program run by the old initrd (which was called
> /initrd, not /init)". Did you mean /linuxrc? I don't recall seeing
> /initrd anywhere else.

Yeah, that's linuxrc.

> And finally, could you add some bigger warnings about rootfs being
> ramfs, a non-swappable device?

There are patches floating around to make it tmpfs if you have tmpfs built 
into the kernel.  I keep thinking they've been integrated.  (This is the 
point of tmpfs.)

> The file does say that initramfs is 
> extracted to rootfs, an instance of ramfs. But I didn't read the file
> that carefully the first time...

It should be possible for this to be tmpfs.  When did this last crop up...

http://lkml.org/lkml/2006/7/30/120

Dunno if it got integrated or not, but there's a start...

> I made a /init that extracts cpios (gziped and bziped) in / to a tmpfs,
> moves all remaining files to the tmpfs, and executes the new init, if
> anyone is interested.

The proper thing to do is patch the kernel so initramfs is a tmpfs.

Rob
-- 
"Perfection is reached, not when there is no longer anything to add, but
when there is no longer anything to take away." - Antoine de Saint-Exupery