On 07/24/2013 02:09 AM, Steffen Trumtrar wrote: > Hi! > > Embedded devices often use multiple SD/MMC devices as boot/rootfs disks. > Some of them are removable, some not. If the removable cards are not > present, but are probed before the non-removable ones, the indexing > scheme changes. This makes it harder to hard-code the rootfs in the > cmdline. > > First solution I came up with was the alias-node in DT. > I guess my implementation is pretty hacky and ugly, but you can get lost > pretty fast in the whole mmc stack. > For example, the second patch should use "card->host->index" instead of parsing > the alias again, I guess. I'm not sure why it currently doesn't though. This has been discussed a few times before and rejected IIRC. One issue is that block device ID is actually decoupled from host controller ID anyway, e.g. if a removable device is mounted, removed, and then re-plugged the new device can get a different ID, so this approach doesn't really work in all cases anyway. > So, if there is a better place or solution to specify a reliable ordering > of mmc devices, please let me hear it. root=UUID=xxx or root=PARTUUID=xxx are the best solution. With recent U-Boot, you can enable and use the "part" command to find the partition UUID automatically, and hence not need to hard-code anything. Something similar could presumably be implemented for other bootloaders. -- 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
