what step in kernel "make install" creates the initrd.img file?

[Robert P. J. Day]

  while this is obviously a kernel building-related question, since it
happens in userspace, i thought i'd ask here since it might be
ubuntu-specific.

  using a fairly straightforward recipe, i'm configuring and building
and installing a new kernel on my 64-bit ubuntu 11.10 system.  all
that works just fine.  after the build, i install the modules and the
kernel itself with the standard commands:

  $ sudo make modules_install
  $ sudo make install

now i'm trying to figure out precisely what step created the
corresponding initrd.img file for the new kernel as i'm poking around
in that file (a compressed cpio archive) and i'm convinced it could do
with a little improvement.  in particular, i'm looking at the
top-level "init" script and i think it could be more informative in
terms of error messages, but that's not the point.

  all i want to know is, who or what creates that initrd.img file?
historically, i was used to the "mkinitrd" command but that's not even
on my system.  i can see "mkinitramfs" but i don't see where that's
being invoked anywhere in the kernel source tree.

  i'm sure i'm missing something obvious.  what creates that file, and
where does it get its default contents from?  thanks.

rday


-- 

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Robert P. J. Day                                 Ottawa, Ontario, CANADA
                        http://crashcourse.ca

Twitter:                                       http://twitter.com/rpjday
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