[PATCH v2 0/3] Support IPMI "Boot Initiator Mailbox"

Samuel Mendoza-Jonas sam at mendozajonas.com
Tue Dec 11 13:40:43 AEDT 2018

Add support for the IPMI Get/Set System Boot Options command parameter
7, "Boot Initator Mailbox", to parse an alternate boot order

A brief description of the mailbox for interested BMC people below; for
details see section 28.13 in the IPMI spec.

Petitboot already takes advantage of the Get/Set System Boot Option
commands to recognise "boot overrides" that have been set. Specifically
this uses parameter 5, "boot flags", of the command as described by Table
28, "Boot Option Parameters" in the IPMI spec. These boot flags are
limited to generic options such as "boot from disk", "boot from network",

What this series does it take advantage of parameter 7, "boot initiator
mailbox", in the same command. The difference here is that this is just a
bunch of space we can put something into. In particular we're using it to
hold a "petitboot,bootdevs=..." parameter the same as we would in NVRAM.

The content of parameter 7 is
	1 byte: block number
	2-17 bytes: block data

The BMC is required to hold *at least* 80 bytes of data, which means 5
blocks (16 bytes * 5 = 80 bytes).

The BMC is also required to set the first 3 bytes of the first block to
an IANA Enterprise ID Number. This series recognises the IBM number (2)
so the first three bytes must be 2, 0, 0 (least-significant first).

So to store the string "petitboot,bootdevs="net usb disk" the format of
the blocks would be:

0:	|2|0|0|p|e|t|i|t|b|o|o|t|,|b|o|o|
1:	|t|d|e|v|s|=|n|e|t| |u|s|b| |d|i|
2:	|s|k| | | | | | | | | | | | | | |

The string must be null-terminated but the remaining buffer contents do
not necessarily need to be set.
Petitboot will request up to 255 blocks (stopping when it first receives
an error) and then use this string if it is present in order to set the
boot order. I would *highly* recommend a BMC supports well over 5 blocks
so that we can fit disk UUIDS and LV names.

Each block is selected individually, eg. Petitboot will send several
requests like,
	get-sys-boot-option, parameter 7, block 0
	get-sys-boot-option, parameter 7, block 1
	get-sys-boot-option, parameter 7, block 2

And the BMC must return the corresponding block. Petitboot will similarly
send set-sys-boot-option commands to set the buffer (to clear it for

The script in patch two lays out the raw format for get & set to use with
ipmitool, and basically shows what the BMC would need to expect and how
to respond.

These details can be found in section 28.13 in v2 rev1.1 of the IPMI
spec, and page 398 specifically for the mailbox.

Changes in v2:
Update get_ipmi_boot_mailbox() to support up to 255 blocks and partial
reads since the spec says it's possible.
Fixup some error messages in the helper utility.
Cleanup an error condition and support 255 blocks in

Samuel Mendoza-Jonas (3):
  discover/platform-powerpc: read bootdev config from IPMI boot mailbox
  utils: Add helper to send mailbox request
  ui/ncurses: Add option to clear IPMI boot mailbox

 discover/platform-powerpc.c   | 257 ++++++++++++++++++++++++++++++++++
 discover/platform.c           |   2 +-
 discover/platform.h           |   2 +
 lib/pb-config/pb-config.c     |   1 +
 lib/pb-protocol/pb-protocol.c |   6 +
 lib/types/types.h             |   1 +
 ui/ncurses/nc-config.c        |  49 ++++++-
 utils/ipmi-mailbox-config.py  | 166 ++++++++++++++++++++++
 8 files changed, 482 insertions(+), 2 deletions(-)
 create mode 100755 utils/ipmi-mailbox-config.py


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