All, I'm working on using aufs on the Intel Edison maker board. I've been able to use edison_src to patch and add aufs to the kernel. I can mount and use aufs directories on the board.
I've been struggling for the better part of a couple of days trying to crowbar in aufs as the rootfs; but I can't seem to get it to work right. Edison uses a Linux 3.10.17 kernel with systemd as the init manager. My experience with systemd is as a newbie. The issue I'm trying to solve is as follows: I want to allow controlled updates to the Edison rootfs (/) . IE when Intel releases a new update; I want to be able to install it. I want to use AUFS to have the Intel rootfs as read-only; but I need and want to be able to compile new software and have it installed to the AUFS root as an overlay. Example: Intel's rootfs uses busybox's shell... I want to be able to compile/install/use bash. Why not just stick with the existing rootfs and deal with being stale? Simply put - IMHO, Intel made a mistake in putting together the emmc image for the product. They put the rootfs at a limit of ~524MB and allowed the /home filesystem to grow the remainder of the emmc. So the home filesystem can grow to ~2.4GB while the more important rootfs is limited. Maybe they had a reason; but it has the unfortunate side effect of not allowing me to install the "full" build set I want. I started down the road of creating a aufsroot inside the home filesystem. I wanted to use the following mount options w/ aufs: br:/ro=ro:/home/aufsroot=rw / but systemd doesn't seem to want to mount the rootfs in ro.... nor does it want to mount the aufs to / Here's a test systemd file I tried to use; it also fails to mount at boottime; but will mount if I type: systemctl start rootfsrw.mount from the console. # /etc/systemd/system/default.target.wants/rootfsrw.mount [Unit] Description = AUFS disk #After=home.mount After=dev-mmcblk0p10.device #the home filesystem partition [Mount] What=none Where=/rootfsrw Type=aufs Options=br:/=ro:/home/aufsroot=rw Here is the Edison's fstab: rootfs / auto nodev,noatime,discard,barrier=1,data=ordered,noauto_da_alloc 1 1 proc /proc proc defaults 0 0 devpts /dev/pts devpts mode=0620,gid=5 0 0 usbdevfs /proc/bus/usb usbdevfs auto 0 0 tmpfs /run tmpfs mode=0755,nodev,nosuid,strictatime 0 0 tmpfs /var/volatile tmpfs defaults 0 0 /dev/disk/by-partlabel/boot /boot auto noauto,x-systemd.automount,nosuid,nodev,noatime,discard 1 1 /dev/disk/by-partlabel/home /home auto noauto,x-systemd.automount,nosuid,nodev,noatime,discard,barrier=1,data=order ed,noauto_da_alloc 1 1 Looking for suggestions / thoughts / ideas, John
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