Public bug reported:

qemu-slof 20140630+dfsg-1ubuntu1~14.04 from trusty-updates appears to
corrupt memory during some network boot operations, while 20140630+dfsg-
1ubuntu1 (utopic, identical source, but built with gcc 4.9 rather than
trusty's 4.8) works fine.

For example, a "boot net" that performs a TFTP download (even if it
connects but fails, eg. because the file doesn't exist, but not if it
fails to DHCP or connect at all) causes a subsequent "boot cdrom" to
fail. http://paste.ubuntu.com/12710600/ has examples to reproduce the
good and bad cases, no manual DHCP/TFTP setup required.

Other manifestations of memory corruption include a TFTP-booted GRUB
working fine except that the MAC address that GRUB uses for its own TFTP
operations has its last octet replaced with 0xd1. This was originally
noticed when MAAS failed to boot KVM instances, as it assumed the MAC
that GRUB used matched the one that Linux knew about.

Both cases are fixed by using a qemu-slof built with gcc 4.9 instead of
the 4.8-built archive version.

A tcpdump excerpt covering the final TFTP packet loading GRUB itself,
and the first ARP from within GRUB:

  04:01:23.536384 52:54:00:55:40:13 (oui Unknown) > 52:54:00:17:ed:f1 (oui 
Unknown), ethertype IPv4 (0x0800), length 60: 10.10.0.107.2001 > 
10.10.0.2.38623: UDP, length 4
  04:01:23.876989 52:54:00:55:40:d1 (oui Unknown) > Broadcast, ethertype ARP 
(0x0806), length 60: Request who-has 10.10.0.2 tell 10.10.0.107, length 46

** Affects: slof (Ubuntu)
     Importance: Undecided
         Status: Invalid

** Affects: slof (Ubuntu Trusty)
     Importance: High
         Status: Triaged

** Also affects: slof (Ubuntu Trusty)
   Importance: Undecided
       Status: New

** Changed in: slof (Ubuntu)
       Status: New => Invalid

** Changed in: slof (Ubuntu Trusty)
   Importance: Undecided => High

** Changed in: slof (Ubuntu Trusty)
       Status: New => Triaged

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Server Team, which is subscribed to slof in Ubuntu.
https://bugs.launchpad.net/bugs/1503929

Title:
  trusty-updates qemu-slof network boot breaks subsequent OpenFirmware
  operations

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