[U-Boot] [PATCH 0/2] api: extend accessible set of block device attributes

[Detlev Zundel <dzu@denx.de>]

Hi Che-liang,

> I am working on an open source secure bootloader based on U-Boot.
> Mostly I wrote boot logic (by boot logic I mean prompting user and
> listing available devices sort of things). If you see U-Boot as a
> platform, you can think of my project as an application running on top
> of U-Boot, except that my application is statically linked with
> U-Boot.

Usually the (old or new) API is used to separate the application from
the GPLed U-Boot codebase to allow for proprietary applications.  If you
plan to link your application statically to U-Boot anyway, then I think
that using the (external) API is not a good way to move forward.

> The boot logic is running on ARM and x86. Through the project I have
> learned that certain APIs would be helpful, such as enumerating all
> available block device and drawing bitmaps on screen regardless of
> which driver (video or LCD) you are using.

Yes, I think what you actually are looking for is a proper device model
in U-Boot.  Actually we are in dire need for something like this in the
whole of U-Boots codebase and we talk about it for a very long time (see
for example [1]).  This would ease progress in multiple
areas, where currently we hack around this.  See for example the
SERIAL_MULTI code base or NET_MULTI.  Both are isolated solutions for
the same problem.  As you note, video and block devices will also
profit - USB will be another instance.

> It was probably a misleading finding when I searched the code base: I
> saw only the external apps API implemented an API for enumerating
> available block device. So I thought improving the external apps API
> was the right place to go.
>
> Alternatively (if not go the external apps API), we could have like
> common/cmd_enum_block_dev.c that does what I am planning to do, and I
> am happy to do this. What do you think?

I think we should aim at a pretty generic device interface.  Currently I
would think that this also needs to fit into the "configure U-Boot
through the device tree" topic.  The one will profit from the other.

As far as I know, Marek (on CC) is working towards this device tree
model also.  Coordinating the efforts will be a good thing.

Thanks!
  Detlev

-- 
Perfecting oneself is as much unlearning as it is learning. 
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