Re: [PATCH 4/5] RFC: mmc: block: Convert RPMB to a character device

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>>> Currently the RPMB partition spawns a separate block device
>>> named /dev/mmcblkNrpmb for each device with an RPMB partition,
>>> including the creation of a block queue with its own kernel
>>> thread and all overhead associated with this. On the Ux500
>>> HREFv60 platform, for example, the two eMMCs means that two
>>> block queues with separate threads are created for no use
>>> whatsoever.
>>
>> Yikes!  What an amazingly stupid design decision.
>
> Unfortunate, there is more. :-)
>
> We are actually registering at least three more block devices per eMMC
> card (two boot partitions, and one general purpose partition). Except
> for the main partition of course.

Little correction, there are 4 general purpose partition, not one.

>
> The difference compared to rpmb from the above, is that those are
> actually general read/write partitions.
>
> So all these partitions are on the same eMMC card, but being I/O
> scheduled separately because there are separate block devices. Yeah,
> starvation, latency, etc - all bad things comes with it. :-)

Actually the worst issue is that emmc is single headed and all the security
devices and VMs has to go via host for their data.
>
> My point is, this is only the first step in re-working and fixing this
> - and we really appreciate your review!
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