I recently noticed with 4.4 based kernel's Android's userspace wasn't able to properly detect micro-SD cards when they were inserted.
This is due to vold not being able to access /sys/module/mmcblk/parameters/perdev_minors See: http://androidxref.com/6.0.1_r10/xref/system/vold/Disk.cpp#49 Looking into it, it seems commit 829b6962f7e3cfc ("mmc: block: don't use parameter prefix if built as module") changed the behavior, resulting in the userspace path changing to: "/sys/module/mmc_block/..." This seems like an ABI regression, which is breaking existing userspace. So... Probably something to revert? thanks -john
