The design of mdev (mini-udev for busybox).

Rob Landley rob at landley.net
Tue Dec 6 03:30:20 UTC 2005


On Monday 05 December 2005 17:26, Paul Fox wrote:

>  > It doesn't, that's just where I put it.  You can point
>  > CONFIG_INITRAMFS_SOURCE to anything.  Feed it an absolute path, etc.
>
> i see.  i think i got that impression from your doc page:
>     "Note that those two example "file" entries expect to find
>     files named "init.sh" and "busybox" in a directory called
>     "initramfs", under the linux-2.6.* directory."

My example does, yes.

> presumably i should have followed the pointer in the next sentence
> to get the complete answer.  :-)

I haven't really played with it that much.  My example is what I do.  That 
said, you'd be amazed what you can do with a directory symlink...

>  > > all this is why it feels like the two mechanisms are solving
>  > > somewhat different problems.  but remember, i'm mostly comparing
>  > > to initrd-based systems, which is what we (like most others) were
>  > > doing before we found the inittar patches -- initramfs may be
>  > > useable in some of these ways as well.  i'm just ignorant of it.
>  >
>  > Initramfs is very different from initrd, and it sounds like
>  > the only thing it doesn't already do that you want is the
>  > TMPFS mount for rootfs.  (And I was pretty sure that had
>
> plus the need for a linker to rebuild.  and 2.4 kernel support.  other
> than that, you're right -- they're identical.  ;-)

I strongly suspect you can rebuild without the linker, even if you're not 
using the external initrd-style version.  I just haven't bothered to work out 
how yet.

Keep in mind I once took apart and reassembled an rpm with "cpio" and "dd" 
because I needed to fix a path in it, and my first experience with a debugger 
was to hack a friend's game binary to give him unlimited gold in "Betrayal at 
Krondor" (tracing back from where it updated the mcga screen ram to draw the 
current gold amount, back through a dozen or so different jump points that 
were probably functionsI didn't have source to, to find a memory location in 
this strange format I had to puzzle out and which I would years later learn 
is how floating point numbers are stored in memory...)

Swapping out a section of an elf binary via shell script?  Not 
intimidating. :)

Rob
-- 
Steve Ballmer: Innovation!  Inigo Montoya: You keep using that word.
I do not think it means what you think it means.



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