Re: kbuild: LDFLAGS_MODULE unusable for external module builds (2.6.23-rc2)

From: Henry Nestler
Date: Wed Sep 26 2007 - 05:56:32 EST

Hello Sam,

Sam Ravnborg wrote:
Hi Henry.

On Tue, Sep 25, 2007 at 11:49:44AM +0200, Henry Nestler wrote:
In reference of git 114f51577724b782a30f4f5ceaee9880de93d776:
kbuild: use LDFLAGS_MODULE only for .ko links
Sam Ravnborg pointed out that Documentation/kbuild/makefiles.txt already
says this is what it's for. This patch makes the reality live up to the
documentation. This fixes the problem of LDFLAGS_BUILD_ID getting into too
many places.
LDFLAGS_MODULE is not usable in module build out of kernel tree since
2.6.23-rc2. LDFLAGS_$@ should use, but does never work. - Not for
external module builds with the option "M=..."

LDFLAGS_MODULE are reserved for architectures and modules be external
or not should never ude LDFLAGS_MODULE.
And LDFALGS_$@ have never been documented to work for modules - dunno
where you have that from.
IIRC we only use LDFALGS_$@ in the ld macro to be used by bootloaders.

What macro should set for linker parameters of foo.o ? I'm not shure.
Have you read:

Yes. This was a *very* helpfull. And many examples spokes about LDFLAGS_$@ there. Not directly described for modules.

From your description you want to add a specific set of options to
the linker in a specific Kbuild file.
This is what EXTRA_LDFLAGS are present to help you with.

As for the:
# Deal with recursive depens of libraries
I am not sure what you mean (despite yout comprehensive description).

depens = lib1 has external dependently from lib2, and lib2 later depends on externals from lib1. The main problem is, how can add multiple lib.a to module?

Please try if EXTRA_LDFLAGS := --start-group lib.a --end-group
will solve your need.

isn't usable. There I have problems with dependencies. dir/lib.a would not build, if lib.a is not in the list "...-objs".

I'm afraid not due to the placement of the --start-group --end-group.
If this does not help you please give me specific examples of how
the ld command-line should be then I can see how we tweak kbuild
to help you.

An abstracted Makefile shows:
obj-y := dir1/ dir2/ dir3/
obj-m := name.ko
name-objs = foo.o dir1/lib.a dir2/lib.a dir3/lib.a
EXTRA_LDFLAGS := --start-group # recursive dependencies of libraries

From short testing was seen the flags ok. The current project Makefile is in [1]. I will try "EXTRA_LDFLAGS := --start-group" without the end-group in the project tree and mail again. Thanks for your help.



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