[Buildroot] using PROJECTs with buildroot

Ulf Samuelsson ulf at atmel.com
Mon Sep 24 14:43:29 UTC 2007

mån 2007-09-24 klockan 14:31 +0200 skrev Bernhard Fischer:
> Ulf?
> Did you receive this mail?
> On Fri, Sep 21, 2007 at 05:33:40PM +0200, Bernhard Fischer wrote:
> >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 with LFS support on
> >BR2_PROJECT=imageB: kernel 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../$"
> >drwxr-xr-x root/root         0 2007-09-19 19:05 ./lib/modules/
> >$ 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?
> >

The project thingy will allow you to share a toolchain
with one set of kernel headers.
You can't have two set of kernel headers.
Then you need to build a separate toolchain.

It looks to me that the user has changed the kernel headers version
between imageA and imageB.
That is illegal, then he needs to rebuild the toolset.

Instead, he should change LINUX26_VERSION
which needs to be done outside menuconfig

> >
> >
> >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

No, these are global stuff which affects the toolchain.
If you have several versions of these, then you need
to have several toolchains.

I keep these constant, and have only a couple of packages in
project_build_arch, like linux, busybox, u-boot and at91-bootstrap.
I build up to 7 boards from the same build_arch and it is much much

The "old" way would require you to have 7 different trees.

> >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.
> >

It is more like 95% in practice.
I have a feeling you don't use the feature, so why argue.

> >If you now take into account that there is a potential
> >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.
> >
Ulf Samuelsson

> >regards,
> >Bernhard
> >_______________________________________________
> >buildroot mailing list
> >buildroot at uclibc.org
> >http://busybox.net/mailman/listinfo/buildroot
> >

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