[Qemu-devel] nvram and boot order

[Anthony Liguori <aliguori@us.ibm.com>]

We discussed nvram and it's interaction with boot order in today's KVM
call.  Here's the outcome.  This list is completely incremental so it's
fine to start with 1-4, for instance, as long as we eventually get to 6.

Today, on x86, we implement up to (5) but we don't persist NVRAM.

1) We should modify QEMUMachine to specify that a machine does not want
   a default boot order.  Ideally, this would be done by adding a new
   default_boot_order that is set to "cad" explicitly in all machines
   allowing a machine to remove that entry.  At any rate, this allows a
   machine to receive a NULL boot order when -boot isn't used and take an
   appropriate action accordingly.

2) In the absence of a persistent NVRAM, a ephemeral NVRAM should be
   generated with a reasonable default boot order.

3) In the absence of -boot or ,bootindex=, the system should boot from
   order specified in NVRAM.

4) If -boot is specified, the parameter should alter the contents of
   NVRAM to change the boot order to what is specified by -boot.

5) If ,bootorder is specified, it should take predence over -boot.

6) ,bootorder= should also alter the contents of NVRAM to determine the
   boot order.

Regards,

Anthony Liguori