[Buildroot] using PROJECTs with buildroot

[Bernhard Fischer <rep.dot.nop@gmail.com>]

Hi,

I'd like to ask how that project thing is supposed to be used and how it
could be fixed (assuming that i'm not doing something wrong, which could
easily be).

Suppose i want to create two images (or BSP's like some call those).

To keep things simple, let's assume that i'm using the same version of
binutils and gcc for all.


BR2_PROJECT=imageA: kernel 2.6.22.6 with LFS support on
BR2_PROJECT=imageB: kernel 2.6.22.1 without LFS

0) I 'rm -rf *_i386 binar*'
1) I configure and build imageA. So far so good.
2) I configure and build imageB. The resulting image looks like this:
$ tar -tvf binaries/imageB/rootfs.i386-20070919.tar | grep "2.6.22../$"
drwxr-xr-x root/root         0 2007-09-19 19:05 ./lib/modules/2.6.22.6/
$ egrep "(2_6_22|PROJECT)" .config
BR2_PROJECT="imageB"
BR2_KERNEL_HEADERS_2_6_22_1=y
# BR2_KERNEL_HEADERS_2_6_22 is not set

Not exactly what i'd have expected.
Perhaps i made a mistake? If so please explain how that would work
properly?



A more general question that i already raised is what the
project_build_arch dir is supposed to be good for. I didn't get an
answer on this question, i think.

I'm questioning it's usefulness because if done properly, nearly all
packages would have to be built there, leaving the "good old" build_arch
directory completely empty.

Your reasoning seems to be along the lines of:
"A package that is customized on a per project basis has to be built in
project_build_arch".

While this may be true, customization that qualifies for building in
project_build_arch dir includes these toggles:

1) LFS on/off
2a) locale on/off
2b) wchar on/off
3) IPv6 on/off

These alone would lead to the build_arch dir to be nearly empty, but
let's assume that it would still contain 25% of the packages since those
would be locale+wchar+IPv6+LFS agnostic, fine.

If you now take into account that there is a potential
4) TARGET_CFLAGS
then suddenly project_build_arch dir would be the exact same thing
build_arch was before, leaving build_arch empty (the exact same thing we
had before that project thing, just back then the project_dir was the
empty -- non-existing one -- and build_arch was populated).

It would be very kind if you would share your thoughts on these issues.

regards,
Bernhard