[U-Boot] [PATCH v2 2/2] cmd: Add 'bcb' command to read/modify/write BCB fields

[Simon Glass]

Hi Eugeniu,

On Mon, 20 May 2019 at 01:23, Eugeniu Rosca <erosca at de.adit-jv.com> wrote:
>
> Hi Simon
> cc: Sam, Igor, feel free to correct/augment anything of below
>
> On Sat, May 18, 2019 at 10:33:02AM -0600, Simon Glass wrote:
> > Hi Eugeniu,
> >
> > On Fri, 17 May 2019 at 08:46, Eugeniu Rosca <erosca at de.adit-jv.com> wrote:
> > >
> > > 'Bootloader Control Block' (BCB) is a well established term/acronym in
> > > the Android namespace which refers to a location in a dedicated raw
> > > (i.e. FS-unaware) flash (e.g. eMMC) partition, usually called "misc",
> > > which is used as media for exchanging messages between Android userspace
> > > (particularly recovery [1]) and an Android-capable bootloader.
> > >
> [..]
> >
> > Where is this documented? Perhaps it should go in README.avb2?
>
> README.avb2 is solely about the "verified/secure" booting of Android,
> while the 'bcb' command proposed in this patch can be useful both in
> verified boot scenarios (e.g. full-featured U-Boot builds), as well
> as in non-avb ones (e.g. development, PoC, demos, custom
> configurations). Thus, I think that README.avb2 is not the best
> place for 'bcb'.
>
> More generally, as somebody who uses git as an extension of himself, I
> am quite happy with commit-only documentation. OTOH, for those who
> receive U-Boot in tarballs or expect source-level docs/tutorials, I
> agree that having the 'bcb' described in a README might be helpful.
>
> I can identify two Android-dedicated README files, but none of them
> seems to be suitable for the new command:
>  - doc/README.android-fastboot
>  - doc/README.avb2
>
> Igor, Sam, what's your view on the above? Would you suggest creating
> a doc/README.android-bcb or there is a more elegant solution to it?

How about a new README.android which links to the other two and adds
your new info?

>
> >
> > Should it default to enabled if avb is used?
>
> I think at this specific moment in time, 'bcb' is orthogonal (meaning it
> is neither a direct, nor a reverse dependency) to any other Android
> feature in U-Boot. This could be re-assessed, if platform maintainers
> start to rely on 'bcb' in their U-Boot environments on regular basis.

OK. Also is there a sandbox driver for this? We should have a test.

Regards,
Simon