On 05/22/2014 09:30 AM, Sascha Hauer wrote: > Hi all, > > The wish to have persistent MMC block device names for passing a suitable > root=/dev/mmcblkX option came up several times already and has been discussed > at least in these threads: > > http://lists.infradead.org/pipermail/linux-arm-kernel/2012-July/109984.html > https://www.mail-archive.com/linux-mmc@xxxxxxxxxxxxxxx/msg22104.html > http://comments.gmane.org/gmane.linux.kernel.mmc/21519 > > Several patches have been proposed to nail the slot index to a known number. > Arguments against these patches were: > > - Use an initrd and locate the correct root device there > even Thomas who suggested this admitted this would be painful to do > - use root=UUID= or root=PARTUUID= > This generally works but has an important downside. With the UUID > approach devices which should boot from the internal eMMC may start > booting from an external SD slot when somebody deliberately inserts > a SD card with the same UUID. > > The following patches should have the technical issues fixed. It works > by counting the mmc aliases in the devicetree during initialization of > the mmc framework. Those slot numbers will never be assigned to other > hosts. Does it solve the following, which AFAIK has always been the primary argument against aligning block device IDs with controller IDs: - User inserts SD card into MMC controller ID (or alias) 1. - /dev/mmcblk1 now exists - Mount /dev/mmcblk1 on /mnt/tmp - User removes that SD card - /dev/mmcblk1 still exists, since it's mounted so can't be deleted after the card removal. - User inserts SD card into MMC controller ID (or alias) 1. - /dev/mmcblkN (N is something other than 1) now exists Now, the block device ID must be != the original ID, since two block devices exist. -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
