Am 19.06.2016 um 01:20 schrieb Daniel Golle: > In MBR there used to be an 'active' flag stored for each partition. > Maybe it'd be nice to introduce something similar to mark UBI volumes > to be the default rootfs. > Currently we solve this issue by convention: If a volume is named > 'rootfs' it is automatically mounted during boot. Depending on the > filesystem in use a ubiblock device has to be created as well. > This is mostly just the continuation of the existing naming convention > of mtd partitions, a patch OpenWrt is carrying around for a long > while already. > To support the same on UBI, another set of patches was made. Sorry, I still have troubles to understand your use case. Both of you seem to hate the kernel command line for reasons I don't fully understand so far. > I agree that there should be a way to pass this through the of_node > of the mtd partition which is defined in the device tree. > Selecting to-be-ubi-attached mtd partitions in device-tree would > replace patch: > > https://git.lede-project.org/?p=source.git;a=blob;f=target/linux/generic/patches-4.4/490-ubi-auto-attach-mtd-device-named-ubi-or-data-on-boot.patch What is the need of this? Use use the kernel command line to tell UBI from which MTD to attach. > To auto-select the rootfs, we currently carry another bunch of patches > > https://git.lede-project.org/?p=source.git;a=blob;f=target/linux/generic/patches-4.4/491-ubi-auto-create-ubiblock-device-for-rootfs.patch Same question here. > https://git.lede-project.org/?p=source.git;a=blob;f=target/linux/generic/patches-4.4/492-try-auto-mounting-ubi0-rootfs-in-init-do_mounts.c.patch Ditto. > https://git.lede-project.org/?p=source.git;a=blob;f=target/linux/generic/patches-4.4/493-ubi-set-ROOT_DEV-to-ubiblock-rootfs-if-unset.patch Ditto. > This is more or less filesystem-agnostic and works fine as long as > there is only one volume called 'rootfs' and this volume is always > used as rootfs. > > Dual-boot setups will need some way to pass the active rootfs volume to > the kernel. While I agree that this is possible by appending or > prepending to the cmdline string passed to the kernel, this either > limits the users' ability to manually specify the rootfs using the > cmdline or becomes a more complex task to only append/prepend the > cmdline in case the user-defined string doesn't already contain > relevant parameters... Sorry, but this is just a tooling problem and not to be addressed in the kernel. There is also the possibility to use an initramfs (either as file or embedded in the kernel) if the mount/attach logic becomes *really* complicated... > Thus it'd be nicer to flag the default rootfs volume via the device- > tree. As I said, as far I'm informed device tree is for configuring Linux, it describes the hardware. We also don't have LVM, DM or iSCSI bindings in DT. ;) Maybe device tree folks will tell more... Thanks, //richard -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
