V2 Incremental image generation(rpm based rootfs)

Changes of V2:

* Move the config sample from meta-yocto/conf/local.conf.sample to meta-yocto/conf/local.conf.sample.extended as Saul suggested.

Testing:
1) Enable INC_IMAGE_GEN = "1" in conf/local.conf
2) $ bitbake core-image-sato

* Test when remove some pkgs
a) Save the modify time of file which is in tmp/work/qemux86_64-poky-linux/core-image-sato-1.0-r0/rootfs/dev/.
b) Edit meta/recipes-sato/images/core-image-sato.bb, remove ${SATO_IMAGE_FEATURES} from IMAGE_FEATURES.
c) bitbake core-image-sato

Result: The project built well, check the modify time of the file which is in tmp/work/qemux86_64-poky-linux/core-image-sato-1.0-r0/rootfs/dev/, They should be the same to step a)'s, which means that these files were note newly created.

* Testh when add some pkgs
a) Save the modify time of file which is in tmp/work/qemux86_64-poky-linux/core-image-sato-1.0-r0/rootfs/dev/.
b) Edit meta/recipes-sato/images/core-image-sato.bb, add the ${SATO_IMAGE_FEATURES} back to IMAGE_FEATURES.
c) bitbake core-image-sato

Result: The project built well, check the modify time of the file which is in tmp/work/qemux86_64-poky-linux/core-image-sato-1.0-r0/rootfs/dev/, They should be the same to step a)'s, which means that these files were note newly created.

* Test when edit a pkg
a) bitbake bzip2 -cclean
b) rm -f rm -f sstate-cache/sstate-bzip2-*
c) Edit meta/recipes-extended/bzip2/bzip2_1.0.6.bb
d) bitbake core-image-sato
Result: The project built well, and check:
tmp/work/qemux86-poky-linux/core-image-sato-1.0-r0/temp/log.do_rootfs
Only the bzip2 has been re-installed

// Robert

The following changes since commit f5aa3bbda623c8fae3a761d72fddc95631ad0706:

coreutils: ensure --color works so DEPEND on libcap (2011-12-24 10:05:47 +0000)

are available in the git repository at:
git://git.pokylinux.org/poky-contrib robert/inc_image_gen
http://git.pokylinux.org/cgit.cgi/poky-contrib/log/?h=robert/inc_image_gen

Robert Yang (2):
Incremental image generation(rpm based rootfs)
Incremental image generation(Add config sample)

 meta-yocto/conf/local.conf.sample.extended |    7 +++
 meta/classes/image.bbclass                 |   11 ++++-
 meta/classes/package_rpm.bbclass           |   72 ++++++++++++++++++++++++----
 3 files changed, 78 insertions(+), 12 deletions(-)

1.7.4.1