Incremental rpm image generation

Incremental rpm image generation, the rootfs would be totally removed and
re-created in the second generation by default, but with
INC_RPM_IMAGE_GEN = "1", the rpm based rootfs would be kept, and will do
update(remove/add some pkgs) on it.

NOTE: This is not suggested when you want to create a productive rootfs

For example:
  1) Add the follow config option to a conf file:
     INC_RPM_IMAGE_GEN = "1"

  2) bitbake core-image-sato
     modify a package
     bitbake core-image-sato

The rootfs would not be totally removed and re-created in the second
generation, it would be simply updated based on the "package".

Implatation:
1) Figure out the pkg which need to be removed or re-installed, then use
'rpm -e to remove the old one. Use the rpm's BUILDTIME to determine
which pkg has been rebuilt.

2) Figure out the pkg which is newly added, and use 'rpm -U' to install
it.

This only for the rpm based rootfs, the deb and ipk based rootfs would
be done later.

[YOCTO #1651]

(From OE-Core rev: 575ba3c9e153a1d8ac228a99a03ca2df5fbca151)

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 9 insertions, 2 deletions

diff --git a/meta/classes/image.bbclass b/meta/classes/image.bbclass
index 295b653c97..3034725ac2 100644
--- a/meta/classes/image.bbclass
+++ b/meta/classes/image.bbclass
@@ -134,15 +134,22 @@ do_rootfs[umask] = 022
 
 fakeroot do_rootfs () {
         #set -x
-        rm -rf ${IMAGE_ROOTFS}
+    # When use the rpm incremental image generation, don't remove the rootfs
+    if [ "${INC_RPM_IMAGE_GEN}" != "1" -o "${IMAGE_PKGTYPE}" != "rpm" ]; then
+        rm -rf ${IMAGE_ROOTFS}
+    fi
         rm -rf ${MULTILIB_TEMP_ROOTFS}
         mkdir -p ${IMAGE_ROOTFS}
         mkdir -p ${DEPLOY_DIR_IMAGE}
 
         cp ${COREBASE}/meta/files/deploydir_readme.txt ${DEPLOY_DIR_IMAGE}/README_-_DO_NOT_DELETE_FILES_IN_THIS_DIRECTORY.txt
 
-        if [ "${USE_DEVFS}" != "1" ]; then
+    # If "${IMAGE_ROOTFS}/dev" exists, then the device had been made by
+    # the previous build
+        if [ "${USE_DEVFS}" != "1" -a ! -r "${IMAGE_ROOTFS}/dev" ]; then
                 for devtable in ${@get_devtable_list(d)}; do
+            # Always return ture since there maybe already one when use the
+            # incremental image generation
                         makedevs -r ${IMAGE_ROOTFS} -D $devtable
                 done
         fi