path: root/meta/classes/fs-uuid.bbclass
diff options
authorPatrick Ohly <patrick.ohly@intel.com>2015-09-03 20:42:32 +0200
committerRichard Purdie <richard.purdie@linuxfoundation.org>2015-09-06 15:24:26 +0100
commit1e29d77d0d33ee216b43022439876863f0db39bb (patch)
tree7ea393243cee6ac458135024ae913050c848f9b9 /meta/classes/fs-uuid.bbclass
parent7fa76bd923fd643cf0984077321d6064d8ec3a2b (diff)
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=<<uuid-of-rootfs>>". 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 <patrick.ohly@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Diffstat (limited to 'meta/classes/fs-uuid.bbclass')
1 files changed, 24 insertions, 0 deletions
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 <<uuid-of-rootfs>> 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 = '<<uuid-of-rootfs>>'
+ if UUID_PLACEHOLDER in string:
+ uuid = get_rootfs_uuid(d)
+ string = string.replace(UUID_PLACEHOLDER, uuid)
+ return string