Re: [PATCH v4 0/8] Replay Protected Memory Block (RPMB) subsystem

[Arve HjÃnnevÃg]

On Wed, Jun 1, 2016 at 2:41 PM, Tomas Winkler <tomas.winkler@xxxxxxxxx> wrote:
> Few storage technology such is EMMC, UFS, and NVMe support RPMB
> hardware partition with common protocol and frame layout.
> The RPMB partition cannot be accessed via standard block layer, but
> by a set of specific commands: WRITE, READ, GET_WRITE_COUNTER, and
> PROGRAM_KEY.
>...

If the same protocol is used by all these standards, why not export it
directly (including the RESULT_READ command or not even knowing the
command types)? While I would prefer an rpmb specific interface over
the existing raw mmc command interface, all I need is an rpmb
operation that lets me send and receive buffers without interruption.
You can find our exiting user-space code here at
https://android.googlesource.com/platform/system/core/+/master/trusty/storage/proxy/rpmb.c.
If you use an interface more similar to this, I think your emmc and
ufs specific code would be simpler. Also, if you don't need the
in-kernel interface, the kernel would not need to know the details of
the rpmb protocol at all.

I have not tested your code, but it looks like we would have to modify
the storage proxy to interpret the data it currently passes through
and remove all RESULT_READ packets.

-- 
Arve HjÃnnevÃg