From 1e29d77d0d33ee216b43022439876863f0db39bb Mon Sep 17 00:00:00 2001 From: Patrick Ohly Date: Thu, 3 Sep 2015 20:42:32 +0200 Subject: boot loader: support root=UUID As mentioned when introducing the VM images (https://bugzilla.yoctoproject.org/show_bug.cgi?id=7374), the resulting images only work when the image is mounted as a disk that results in the hard-coded path (/dev/sda in the current default). Using the file system UUID to find the rootfs is more flexible. To enable this for boot-direct.bbclass and thus image-vm.bbclass (aka FSTYPEs vdi/vmdk/qcow2), set SYSLINUX_ROOT = "root=UUID=<>". The rootfs image must use an ext file system. The special string will get replaced in the APPEND line with the actual UUID when the boot loader (grub-efi, syslinux or gummiboot) writes the boot loader configuration files. At that time, the rootfs image has already been created and its UUID can be extracted using "tune2fs -l", which also should be available because the e2fsprogs-native tools were needed to create the image in the first place. Signed-off-by: Patrick Ohly Signed-off-by: Richard Purdie --- meta/classes/fs-uuid.bbclass | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) create mode 100644 meta/classes/fs-uuid.bbclass (limited to 'meta/classes/fs-uuid.bbclass') diff --git a/meta/classes/fs-uuid.bbclass b/meta/classes/fs-uuid.bbclass new file mode 100644 index 0000000000..bd2613cf10 --- /dev/null +++ b/meta/classes/fs-uuid.bbclass @@ -0,0 +1,24 @@ +# Extract UUID from ${ROOTFS}, which must have been built +# by the time that this function gets called. Only works +# on ext file systems and depends on tune2fs. +def get_rootfs_uuid(d): + import subprocess + rootfs = d.getVar('ROOTFS', True) + output = subprocess.check_output(['tune2fs', '-l', rootfs]) + for line in output.split('\n'): + if line.startswith('Filesystem UUID:'): + uuid = line.split()[-1] + bb.note('UUID of %s: %s' % (rootfs, uuid)) + return uuid + bb.fatal('Could not determine filesystem UUID of %s' % rootfs) + +# Replace the special <> inside a string (like the +# root= APPEND string in a syslinux.cfg or gummiboot entry) with the +# actual UUID of the rootfs. Does nothing if the special string +# is not used. +def replace_rootfs_uuid(d, string): + UUID_PLACEHOLDER = '<>' + if UUID_PLACEHOLDER in string: + uuid = get_rootfs_uuid(d) + string = string.replace(UUID_PLACEHOLDER, uuid) + return string -- cgit 1.2.3-korg