Re: [RFC][PATCH] mmc_block: Allow more than 8 partitions per card

From: Austin S Hemmelgarn
Date: Fri Oct 16 2015 - 15:16:24 EST


On 2015-10-16 15:08, Arnd Bergmann wrote:
On Friday 16 October 2015 15:03:29 Austin S Hemmelgarn wrote:
On 2015-10-16 14:40, John Stultz wrote:
From: Colin Cross <ccross@xxxxxxxxxxx>

It is quite common for Android devices to utilize more
then 8 partitions on internal eMMC storage. This patch,
which has been carried for quite awhile in the AOSP common
tree is necessary in order to support such configurations,
so I wanted to submit it for consideration upstream.

Isn't this what CONFIG_MMC_BLOCK_MINORS is for? It does limit you to
256 minors total, and therefore the number of supported MMC's is equal
to 256/CONFIG_MMC_BLOCK_MINORS, but I've never heard of an Android
device with support for more than 4 MMC/SD cards (including eMMC's), and
I would seriously question anyone who has the need for more than 32
partitions on the root device for a phone/tablet/television.

The 256 minor limit is really arbitrary, we should not be limited by
that, and you should have have to decide at compile time whether you
might need many partitions or many devices, even if we believe that
nobody will ever need both at the same time.
I didn't mean to imply that I disagree with any of that, I was just trying to get the point across that framing the problem this is trying to solve in such limited terms really isn't the best idea, although I could have gone about doing so in a better way.

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