Debugging 3: Pop Quiz Edition

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I'm kinda enjoying these 'debugging' posts (even if no-one else is!), so I thought I'd do one in a different style. I'll just describe the bug. You get to try and explain it.

I have a properly-working Fedora 18 NFS server. It has a directory /export/fedora , containing the Fedora 19 Beta x86-64 DVD ISO image (and nothing else). Its /etc/exports looks like this:

/export 192.168.1.0/24(ro,sync,insecure,root_squash,no_subtree_check,fsid=0) /export/fedora 192.168.1.0/24(rw,nohide,sync,insecure,root_squash,no_subtree_check)

Assume no issues on the NFS server side.

Now:

  1. If I boot the Fedora 19 Beta x86_64 network install image and append the parameter 'inst.repo=nfs:192.168.1.105:/fedora' to the boot options, the installer boots, and the ISO on the NFS server is used as the installation repository.
  2. If I boot the Fedora 19 Beta x86_64 network install image and append the parameter 'inst.repo=nfs:192.168.1.105:/export/fedora' to the boot options, the installer boots, and the installation repository is set to Closest Mirror.
  3. If I boot a bare Fedora 19 Beta anaconda kernel/initramfs pair (which is the typical case for a PXE or virt-install installation) and pass the parameter 'inst.repo=nfs:192.168.1.105:/fedora' boot fails due to a failure to mount the NFS repository.
  4. If I boot a bare Fedora 19 Beta anaconda kernel/initramfs pair (which is the typical case for a PXE or virt-install installation) and pass the parameter 'inst.repo=nfs:192.168.1.105:/export/fedora', the installer boots (successfully retrieving the installer itself from the NFS repo), and the installation repository is set to Closest Mirror.

Identify all the factors which together explain the above behaviour.

Note: this has already been debugged and there are 'spoilers available', so if you want to figure this one out for yourself, avoid:

  • recent posts to anaconda-patches-list
  • https://bugzilla.redhat.com/show_bug.cgi?id=958763
  • https://bugzilla.redhat.com/show_bug.cgi?id=968023

  • anaconda IRC logs from this morning

  • the current version of https://fedoraproject.org/wiki/Anaconda/Options

You may refer to this version of Anaconda/Options as it existed before I edited it today, if you like.

Winner gets a full year of the highest paid Fedora support tier. Anyone who cheats gets a full year of texlive maintenance duty. Go!

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