image: add image-combined-dbg helper class

There is IMAGE_GEN_DEBUGFS="1" variable that enables build of
additional rootfs-dbg and additional archive that contains
complimentary symbols files for a given image. But the issue
with this resulting directory and tarball that before use it
has to be combined with original image content. It is required
since all cross debugging tools like gdb, perf, and systemtap
need file system that contains both target executables/libraries
and their symbols. Those tools need to find executable/library
first and through it debuglink note find corresponding symbols
file.

image-combined-dbg when added to USER_CLASSES just copies
final resulting rootfs back into rootfs-dbg creating combined
target and debug symbols rootfs that can be used for debugging
directly.

(From OE-Core rev: 7ccb077f51c9232de70e5c6f9897fd9986e3be9d)

Signed-off-by: Victor Kamensky <kamensky@cisco.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

0 files changed, 0 insertions, 0 deletions