On 18/06/2016 06:21, Adrian Panella wrote: > Hi, some Linksys devices (i.e WRT1900AC, EA4500, EA8500,...) have two > different partitions for dual boot, and an additional partition that > Linksys uses for system config (sysconf). > Each of these partitions is of a considerable size (23-37 mb, varying > between devices). > > As far as I could see, the ports already in Owrt/LEDE (Kirkwook & Mvebu) > use only one partition at a time for the overlayfs, so total 23-37mb > shared among squashfs rom and ubifs overlay. > In some cases the third partition (sysconf) is mounted, but in /mmt, not > taking part in the overlay, and so not directly useful for installing > additional packages. > > I believe that a way to better profit all this available space would be > to leave one partition for the rom squashfs alone (23-37mb there) and > share the 3rd partition between alternative boots as the ubifs overlay > (another 23-37mb here). In total we double the space up to a full 74mb > for packages, reducing the need for extroot. > > > Have you found any serious disadvantage on this approach, and that's why > it is not implemented in mvebu/kirkwood? If so, which one? > > If we leave ubifs outside the image, and only squash in one MTD, does it > add any benefit to have squash image on top of an UBI layer? Erase > counters would be lost between firmware flashes anyway and no other > write would occur in between. On the other hand, in the third MTD (i.e. > sysconf) the erase counters could be preserved between firmware updates, > as the ubi block doesn't need to be recreated each time, and only a > ubiformat could be performed on flash. > > I'm planning on switching ipq806x/EA8500 to this scheme, and would > appreciate opinions first.
sharing a rootfs between 2 different kernels is not good as the kernel modules wont be in sync with the kernel version magic. inside th eubi you will have a squash +overlay which is the best approach imho. we could create a special data area however the kernel should always go hand in hand with its squashfs and overlay area. if you flash the kernel+rootfs from within the running installation then the erase counters will not get lost. _______________________________________________ Lede-dev mailing list Lede-dev@lists.infradead.org http://lists.infradead.org/mailman/listinfo/lede-dev
