dracut "mount.nfs: Connection timed out"

[Russ Allbery]

Hello folks,

I'm updating our FAI build environment to wheezy and trying to get the
first systems to build, and I'm running into trouble with mounting the NFS
root from the build server.  I'm using dracut (rather than live-boot)
since that seems to be the new, preferred option, but it's failing to
mount the NFS root from the FAI build server.

The error I get is:

    mount.nfs: Connection timed out
    dracut Warning: Could not boot.

    Dropping to debug shell.

After the mount fails, mounting the file system from the rescue shell
works fine, so it's not a network problem (at least so far as I can tell):

dracut:/# mount -t nfs leviticus:/srv/fai/wheezy-amd64 /tmp
dracut:/# ls /tmp
bin   dev  home        lib    media  opt   root  sbin     srv  tmp  var
boot  etc  initrc.img  lib64  mnt    proc  run   selinux  sys  usr  vmlinuz

I've tried a wide variety of PXE options.  The ones I'm currently using,
after conferring with the dracut documentation are:

    default fai-generated
    
    label fai-generated
    kernel vmlinuz-3.2.0-4-amd64
    append initrd=initrd.img-3.2.0-4-amd64 ip=dhcp root=nfs:/srv/fai/wheezy-amd64 aufs FAI_FLAGS=verbose,createvt FAI_CONFIG_SRC=nfs://leviticus/srv/fai/config FAI_ACTION=install FAI_SERIAL=0 HOSTNAME=kerberos-mit

(FAI_SERIAL and HOSTNAME are used internally by our hooks.)  It doesn't
seem to get as far as using FAI_CONFIG_SRC; it's failing to mount the root
file system.

I've also tried root=/dev/nfs nfsroot=/srv/fai/wheezy-amd64 (in fact,
that's what I was using initially).

The DHCP options are:

    filename=pxelinux.0
    next-server=leviticus
    tftp-server-name=leviticus

and the kernel loading and whatnot is working fine, so DNS resolution is
working in the boot loader.  /proc/cmdline on the system shows the
contents of append from above, so that part is also working.

Does anyone have any ideas what might be going wrong?

-- 
Russ Allbery (rra at debian.org)               <http://www.eyrie.org/~eagle/>