[PATCH 1/1] drivers: add memory disk support

[Tom Rini]

On Tue, Apr 19, 2022 at 11:55:00PM +0200, Heinrich Schuchardt wrote:
> On 4/19/22 23:26, Tom Rini wrote:
> > On Tue, Apr 19, 2022 at 11:16:41PM +0200, Heinrich Schuchardt wrote:
> > 
> > > In some scenarios it is desirable to package U-Boot with other files into
> > > a single blob. This patch allows to embed a memory disk into the U-Boot
> > > binary. This memory disk can be accessed like any other block
> > > device as 'mem 0'.
> > > 
> > > Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
> > 
> > What's the use case for this, which isn't covered by some combination of
> > U-Boot being in a FIT image and the "load a firmware blob" that we have
> > today?  Thanks!
> 
> "U-Boot being in a FIT image" requires a loader that understands FIT.

Fortunately, that's U-Boot.

> "load a firmware blob" requires a block device or a network file system.

No, we have various cases where we bundle inside of the image various
black boxes, in various ways.

> If you put U-Boot's payload into the U-Boot blob, you need neither a
> separate block device nor a network file system.

What is the use case for this?

> Packaging into U-Boot makes most sense where follow-up binaries are tightly
> integrated:
[re-ordering this list, sorry]
> * delivering device-trees

Yes, we can do that today, select the right one at run time, and even
pass that along to EFI via the appropriate config table entry.

> * adding iPXE

Rather than fetching this from the network, to continue to fetch and
load applications from the network?

> * adding a custom graphical boot manager as EFI application

Why can't this be loaded from the disk?

What I would like to see is the proof of concept / design that makes use
of this, that can't make use of the existing facilities we have for
doing similar concepts already.  Or that aren't something that should be
done within U-Boot, if necessary.

-- 
Tom
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