[Buildroot] [PATCH v3 1/1] Makefile: add target to clean targetfs

[Andreas Naumann <dev@andin.de>]

Am 27.04.2015 um 02:45 schrieb Emeric Vigier:
> If you had some files added to the targetfs (fs-overlay, new packages,
> ...) and you no longer need them, buildroot does not offer a simple way
> to remove these items from the output/target directory. The rule added
> by this commit allows you to clean the targetfs. Issuing 'make'
> afterward will generate a new and clean targetfs.
>
> A section in the documentation is also added. It describes few examples
> when developers could need it. 'make help' is also updated accordingly.
> And full-rebuild section of the documentation is updated with content
> and links.
>

Hi Emeric,

this is very helpful, in fact i have a similar patch running for quite 
some time where I remove target/ and images/ and the corresponding 
stamps. There are some problems though and I want to share my findings 
with you.
To begin with i was not 100% sure if the recreated target is the same as 
after a clean build. So I wrote a small check script which compares the 
original with the re-installed target trees. Here's the comparison i do:

   rsync -rvncl --delete --exclude '*.pyc' --exclude '*.pyo' --exclude 
'tmp/ldconfig/aux-cache' output/target/ target.orig/

As you see it already has some files excluded that are always recreated 
differently.
In addition I need to delete .stamp_host_installed from host-gcc-final* 
to force reinstall of libstdc++ into target (using external linaro 
toolchain).

Another problem that showed up was that some of the package install 
steps dont seem separated very well. E.g. qt5 examples copies everything 
from a certain staging-dir/* to target/..
A later qt5 module also creates files in that staging-dir, so next round 
there's more files in target.

I realize this is due to my way of not deleteing the staging dir any 
longer - I used to in the beginning. If I recall correctly this is 
because I noticed some packages copy files into staging/ during compile 
and these files are then missing after a reinstall. I'm not entirely 
sure though.

So my question is, in your approach, are you certain the re-installed 
staging/ is the same as the original for all packages? Maybe you can run 
some comparison like my rsync line for staging as well.


regards,
Andreas