Optimize the build process

[th0ma7]

The current build process does a full kernel build of the unmodified linux-4.4.x tree (unless i'm missing something). Could it be possible to simply adjust Makefile, copy/modify the config and invoke:

$ make oldconfig
$ make modules_prepare

And then directly call the media_build build script?

Because the following command:
./md_builder.sh -B media -d SYNO-Apollolake
Leeds to a full compilation of build/SYNOAPOLLOLAKE/linux-4.4.x

So I ended up having to directly invoke the media build:

$ cd build/SYNOAPOLLOLAKE/media_build
$ build
make[2]: Leaving directory '/home/th0ma7/git/Embedded-MediaDrivers/build/SYNOAPOLLOLAKE/linux-4.4.x'
./scripts/rmmod.pl check
found 648 modules
make[1]: Leaving directory '/home/th0ma7/git/Embedded-MediaDrivers/build/SYNOAPOLLOLAKE/media_build/v4l'
**********************************************************
* Compilation finished. Use 'make install' to install them
**********************************************************

Note that I tried skipping md_builder.sh -B part and directly invoke media_build but it requires the Makefile and .config pre-adjusted over the linux-4.4.x tree to be done first, which is done by the md_builder.sh -B call.

[b-rad-NDi]

I'll revisit the build system. For apollolake you don't need to compile the full kernel, but for other platforms there are system and/or built-in modules missing, so the whole thing must be built. This is something that must only be done once, no matter how many times the media_build system is updated, so I'm not sure if there's really an issue here.

[th0ma7]

gotcha.
It's just that I much like having procedures which are fully reproducible always and doing a full kernel compilation can be quite long when being done in a VM over my NAS without -j flag with nproc for instance. That being said, compiling only what's necessary using something like:

$ make modules_prepare
$ make modules M=drivers/i2c -j`nproc`
...

But I now realize that this bug entry referred to two things:
a) making compilation faster / more efficient
b) was it intended that the media build to be invoked manually? or is it just me not being patient enough and hitting ctrl-c before the end of the synology DSM kernel compilation and thus the process not invoking the media build automagically afterwards?

[th0ma7]

As an FYI, I've documented how to reproduce the build using your tool (as this could end-up being useful for others):

• https://github.com/th0ma7/synology

[th0ma7]

Build process now entirely reproduced within SynoCommunity PR SynoCommunity/spksrc#4144
Closing the issue.