Re: Make ipconfig.c work as a loadable module.

Russell King
2003-03-07T09:32:06Z

On Fri, Mar 07, 2003 at 01:29:05AM +0000, Chris Dukes wrote:
> If IBM can fit a kernel and a ramdisk containing all the utilities you
> describe and more in smaller than 5M of file for tftp, one would think
> that it could be done on Linux.

Wow. 5MB eh? We currently do NFS-root in 690K.

> > ipconfig.c does more than just configure networking. It's a far smaller
> > solution to NFS-root than any userspace implementation could ever hope
> > to be.
>
> That's nice. Would you mind explaining to us where that would be a
> benefit? Aside from dead header space in elf executables, I'm at
> a loss as to how a usermode implementation must be significantly
> larger than kernel code.

If you're suggesting above that "5MB isn't significantly larger than
the size Linux can do this" then I think I've just proven you wrong.

Lets see - building an ramdisk to mount a root filesystem out of existing
binaries would require from my exisitng systems probably something like:

text data bss dec hex filename
1093047 21224 15560 1129831 113d67 /lib/libc.so.6
515890 22320 16640 554850 87762 /bin/sh
58540 2436 9776 70752 11460 /lib/libresolv.so.2
53685 1476 5488 60649 ece9 /bin/mount
45511 672 432 46615 b617 /bin/sed
42830 624 40 43494 a9e6 /sbin/pump
10783 500 104 11387 2c7b /lib/libtermcap.so.2
8765 444 28 9237 2415 /lib/libdl.so.2

pump isn't really suitable for the task, but I don't have dhcpcd around.
dhcpcd is even larger than pump however.

That's getting on for 2MB vs:

2620 2012 0 4632 1218 fs/nfs/nfsroot.o
8016 380 80 8476 211c net/ipv4/ipconfig.o

about 13K.

Which version is overly bloated?
Which version is huge?
Which version is compact?

Even the klibc ipconfig version is significantly larger than the in-kernel
version - and klibc and its binaries are written to be small.

Note: I *do* agree that ipconfig.c needs to die before 2.6 but I do not
agree that today is the right day.

--
Russell King (rmk@arm.linux.org.uk) The developer of ARM Linux