[PATCH] Initrd Dynamic -- Initramfs's GrandDaddy...(and competition)

Dave Cinege (dcinege@psychosis.com)
Fri, 1 Nov 2002 06:05:12 -0500


Linus,

I am submitting this for inclusion into the pre-2.6 tree.
You've said 'yes' to initramfs. Maybe you'll like this
'ready to go' solution better.

A patch against 2.5.45 is here:
http://ftp.psychosis.com/linux/initrd-dyn/kernelpatches/2.5.45/initrd_dynamic-2.5.45.diff.gz

It has been tested as well I can as 2.5.45 has a new bug in rd.c
with initrd deallocation. It was tested with 2.5.44, A-1, no problems.

To find out if you 'like it' you can view the primary
files involved here: They are already 'post-patched' 2.5.45:
http://ftp.psychosis.com/linux/initrd-dyn/kernelpatches/2.5.45/do_mounts.c
http://ftp.psychosis.com/linux/initrd-dyn/kernelpatches/2.5.45/initrd.c
http://ftp.psychosis.com/linux/initrd-dyn/kernelpatches/2.5.45/untar.c

What this patch does:
One or more tar and/or tar.gz archives can be loaded by a
bootloader, and they will be extracted sequencially to a
tmpfs (ramfs) root.

Rewrote the initrd handling and made the code more modular.

All legacy initrd functions have been removed from do_mounts.c.

do_mounts.c has been greatly cleaned up. (Now ~10K)

All new and legacy initrd related functions are now in initrd.c

We id both un/compressed images/archives and act accordingly.

Better error checking and printk messages

What this has that initramfs doesn't:
Clean up and rewrite of the system already in place.
The use of tar archives
Multiple archive support
Works good, right now

What initramfs has that this doesn't:
Load image from a 'linked' kernel location.
Uses CPIO archives

Why you should include this as the new tmpfs(ramfs) initial root
loading solution:

More robust implementation.

Useful error checking and user output messages

The ability to leave legacy initrd infrasturture
inplace via #ifdef's if needed.

do_mounts.c gets scrubbed up. (Until the day it's purged,
why not!?!)

Tar is in wide spread (general audiences) use. CPIO is not.
People have said Tar is bloated/complex.
Tar == Read header. Determine type. Write file.
CPIO == Read header. Determine type. Write file.
(Look at untar.c. un-cpio'ing is no different. You decide.)

I was here first. ; ) (The first version of this was made
in January 1998 using a minixfs on /dev/ram0)

What I still need to do:
Add loading 'linked image' support ala initramfs (minor work)
Clean some minor things. (Purge mount_tmpfs_root() )
Update docs and comments
Test legacy 'load_ramdisk' style floppy support
Purge anything people want gone (Legacy linuxrc root pivot, etc)

ALL OF THESE WILL BE DONE WITHIN *DAYS* IF YOU SHOW INTEREST

What you should do if you have no desire in this at all:
Please, tell Dave 'no, not at all' so he can go to bed already!

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