help: why can't my hand-rolled kernel mount an LVM root FS?

[Robert P. J. Day]

  disclaimer:  i *really* hate asking what are simple questions on
this list but i've run out of ideas.

  for a while, i was configuring, building, installing and booting new
kernels with the following recipe:
  ... configure, build ...
  $ sudo make modules_install
  $ sudo make install
  $ sudo update-initramfs -c -k 2.6.35-xxxx (whatever)
  $ sudo update-grub

worked great on my previous laptop, where i'd installed ubuntu 10.04
with one monstrous, ext4 filesystem.  all my new, hand-built kernels
worked great.

  recently upgraded to a new laptop and decided to get clever and
created a small ext4 filesystem for /boot, and the rest of root in
/dev/mapper/lynx-root.

  my ubuntu-packaged kernels have no problem booting, but my new
hand-rolled kernel (2.6.35-rc4) chokes and dies thusly when booted in
recovery mode:

md: ... autorun DONE
VFS: Cannot open root device "mapper/lynx-root" on unknown-block(0,0)

  so ... i conclude that somehow i've omitted providing proper LVM2
support somewhere.  in the kernel?  in the initrd?  what awesomely
trivial step have i forgotten?  lvm2 is certainly installed on this
machine and, as i said, the ubuntu packaged kernels have no problem.

  help?

rday

-- 

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Robert P. J. Day                               Waterloo, Ontario, CANADA

        Top-notch, inexpensive online Linux/OSS/kernel courses
                        http://crashcourse.ca

Twitter:                                       http://twitter.com/rpjday
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