Need a protocol to specify boot partition UUID from BMC

[AlexanderAmelkin]

IPMI Specification defines a number of "boot parameters" that can be set via Set System Boot Options command. Among those parameters are:

• 5: Boot flags
• 7: Boot initiator mailbox

The former is fully supported by Petitboot, while the latter isn't. The data contained in the "mailbox" is not specified except for the size and the first four data bytes. It is proposed to develop a specification for this mailbox to be used to communicate additional boot parameters from BMC to Petitboot beyond those settable via "Boot flags". Specifically, a UUID of the desired boot partition needs to be settable.

Support for that will then be added into OpenBMC.

[sammj]

Reading from the spec:

IPMI allows software to use the boot initiator mailbox as a way for a remote application to pass OEM parameters for
additional selection of the boot process and direction of the startup of post-boot software. If additional parameters are not
included, the system boots the primary/first-scanned device of the type specified.

So that could be a nice way of doing a Petitboot/OpenPOWER specific way of specifying individual boot options. Better than just a UUID, we could format the info such that it matches what Petitboot stores in NVRAM.

[jk-ozlabs]

@sammj: good idea - in that case, we'd have free-form flexibility to define any boot option - not just partitions, but also network interfaces, etc.

[causten]

Any chance the free-form could be something that could be executed at the Petitboot prompt? My org wants to run a script from the command line which launches a Redhat Kickstart file. If my suggestion is not compatible with this issue I can open a different one. It just sounds like you are forming some boot features

[AlexanderAmelkin]

@causten, there are just 80 bytes of data in the mailbox. No space for scripts. Besides, it sounds to me like a security hole. What your organization wants sounds a lot like initrd loaded via BOOTP. And, yes, it doesn't look compatible with this issue.

[ghost]

Chris Austen <notifications@github.com> writes:

Any chance the free-form could be something that could be executed at the Petitboot prompt? My org wants to run a script from the command line which launches a Redhat Kickstart file. If my suggestion is not compatible with this issue I can open a different one. It just sounds like you are forming some boot features

Do keep in mind that we explicitly do *not* guarantee anything in the shell environment as ABI. We do say that petitboot plugins will continue to work though.

…

-- Stewart Smith OPAL Architect, IBM.

[causten]

I've opened a new issue for my request. Sorry for the interruption of your current request.

[sammj]

I've put together a WIP of the Petitboot support here: https://github.com/sammj/petitboot/tree/ipmi-mailbox
Assuming I'm reading the spec right that could work as is, but I need to confirm a few details. I wonder if any of the BMCs around here support the mailbox feature.. 🤔

[sammj]

Turns out AMI BMCs support this, eg:

➜  ~ ipmi-fstn3 raw 0x00 0x08 0x07 0x00 0x11 0x11 0x11 0x11 0x11 0x11 0x11 0x11 0x11 0x11 0x11 0x11 0x11 0x11 0x11 0x11
➜  ~ ipmi-fstn3 raw 0x00 0x09 0x07 0x00 0x00
 01 07 11 11 11 11 11 11 11 11 11 11 11 11 11 11
 11 11

Which supports the minimum of 5 blocks. I've updated https://github.com/sammj/petitboot/tree/ipmi-mailbox to match, and I'll post it after some testing.
That's probably enough for OpenBMC to go on, as long as they provide a way for the user to set that buffer, or even set it themselves, everything should hook up fine.

[sammj]

Series posted: http://patchwork.ozlabs.org/project/petitboot/list/?series=79302

[AlexanderAmelkin]

@sammj, the series clearly lack documentation for BMC developers.

Also, is there a way to review/comment the patches there?
I wonder why don't you use GitHub PRs...

[sammj]

Fair point, I'll add some description; it's largely described by the IPMI spec but there's one or two things to consider when setting it for Petitboot.

Petitboot uses the mailing list (https://lists.ozlabs.org/listinfo/petitboot) for development & discussion much like other projects like Skiboot and the kernel. Github tends to be a useful place to track issues and the like :)

[sammj]

I added a bit of description of the mailbox implementation here: https://lists.ozlabs.org/pipermail/petitboot/2018-December/001240.html

[sammj]

Petitboot now supports this via 78c3a04