A few of the cheaper devices I work with have the system firmware, the RPMB, and the primary block device all backed by the same onboard eMMC flash chip. The special ones show up as /dev/mmcblk1boot0 and /dev/mmcblk1rpmb respectively.
The kernel drivers for the eMMC device automatically detect this situation and write-protect these special devices unless you specifically enable writes via a switch in /proc. Calling parted -l however attempts to open these devices read-write. Which fails and generates a dmesg entry that, prior to the 4.14 kernel, was difficult to distinguish from the messages generated by a failing eMMC device. To keep the logs clean and for safety in the case of someone enabling writes to these devices for various reasons, parted should probably do what it can to leave them alone unless specifically instructed to do otherwise. Poking these devices in the wrong way can potentially brick the motherboard, so an extra layer of defense around them would seem prudent. For my own purposes I will simply remove these device nodes from my system as I have no need of them, so I do not personally consider this to be a critical issue. Those who actually make use of these special devices may disagree though. https://dev-nell.com/rpmb-emmc-errors-under-linux.html documents a different issue, but has some code references that may be useful for determining how best to construct a filter for these special devices. LMP
