[Buildroot] [PATCH 2/2] xen: Remove TARGET_CONFIGURE_OPTS from make

[Alistair Francis]

On Sat, Sep 17, 2016 at 7:09 AM, Thomas Petazzoni
<thomas.petazzoni at free-electrons.com> wrote:
> Hello,
>
> On Wed, 14 Sep 2016 01:23:32 +0200, Arnout Vandecappelle wrote:
>> On 13-09-16 22:45, Alistair Francis wrote:
>> > The TARGET_CONFIGURE_OPTS variable resulted in a double definition
>> > error:
>> > <command-line>:0:0: error: "__OBJECT_FILE__" redefined [-Werror]
>> >
>> > Remove the options to avoid the error.
>>
>>  This doesn't look right. TARGET_CONFIGURE_OPTS definitely doesn't
>> contain -D__OBJECT_FILE__ (or you have some very weird stuff in
>> BR2_TARGET_OPTIMIZATION).
>
> It doesn't look right, but it's actually what happens. When we pass our
> TARGET_CONFIGURE_OPTS, what happens is:
>
> /home/thomas/projets/buildroot/output/host/usr/bin/aarch64-linux-gnu-gcc -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -O2 -fomit-frame-pointer -DBUILD_ID -fno-strict-aliasing -std=gnu99 -Wall -Wstrict-prototypes -Wdeclaration-after-statement -Wno-unused-but-set-variable -Wno-unused-local-typedefs -O2 -fomit-frame-pointer -DBUILD_ID -fno-strict-aliasing -std=gnu99 -Wall -Wstrict-prototypes -Wdeclaration-after-statement -Wno-unused-but-set-variable -Wno-unused-local-typedefs -O2 -fomit-frame-pointer -DBUILD_ID -fno-strict-aliasing -std=gnu99 -Wall -Wstrict-prototypes -Wdeclaration-after-statement -Wno-unused-but-set-variable
> -Wno-unused-local-typedefs -DNDEBUG -nostdinc -fno-builtin -fno-common -Werror -Wredundant-decls -Wno-pointer-arith -pipe -g -D__XEN__ -include /home/thomas/projets/buildroot/output/build/xen-4.7.0/xen/include/xen/config.h '-D__OBJECT_FILE__="/home/thomas/projets/buildroot/output/build/xen-4.7.0/xen/xen"' -Wa,--strip-local-absolute -MMD -MF /home/thomas/projets/buildroot/output/build/xen-4.7.0/xen/.xen.d -mcpu=generic -mgeneral-regs-only -I/home/thomas/projets/buildroot/output/build/xen-4.7.0/xen/include -fno-stack-protector -fno-exceptions -Wnested-externs -DGCC_HAS_VISIBILITY_ATTRIBUTE -O2 -fomit-frame-pointer -DBUILD_ID -fno-strict-aliasing -std=gnu99 -Wall
> -Wstrict-prototypes -Wdeclaration-after-statement -Wno-unused-but-set-variable -Wno-unused-local-typedefs -O2 -fomit-frame-pointer -DBUILD_ID -fno-strict-aliasing -std=gnu99 -Wall -Wstrict-prototypes -Wdeclaration-after-statement -Wno-unused-but-set-variable -Wno-unused-local-typedefs -DNDEBUG -nostdinc -fno-builtin -fno-common -Werror -Wredundant-decls -Wno-pointer-arith -pipe -g -D__XEN__ -include /home/thomas/projets/buildroot/output/build/xen-4.7.0/xen/include/xen/config.h '-D__OBJECT_FILE__="asm-offsets.s"' -Wa,--strip-local-absolute -MMD -MF ./.asm-offsets.s.d -mcpu=generic -mgeneral-regs-only -I/home/thomas/projets/buildroot/output/build/xen-4.7.0/xen/include -fno-stack-protector -fno-exceptions -Wnested-externs -DGCC_HAS_VISIBILITY_ATTRIBUTE -S -o asm-offsets.s arm64/asm-offsets.c
> <command-line>:0:0: error: "__OBJECT_FILE__" redefined [-Werror]
> <command-line>:0:0: note: this is the location of the previous definition
> cc1: all warnings being treated as errors
> Makefile:103: recipe for target 'asm-offsets.s' failed
> make[5]: *** [asm-offsets.s] Error 1
>
> So _OBJECT_FILE_ is really defined twice, once incorrectly, and the
> second time correctly.
>
> When we stop passing $(TARGET_CONFIGURE_OPTS), the same compilation
> step looks like this:
>
> /home/thomas/projets/buildroot/output/host/usr/bin/aarch64-linux-gnu-gcc -O2 -fomit-frame-pointer -DBUILD_ID -fno-strict-aliasing -std=gnu99 -Wall -Wstrict-prototypes -Wdeclaration-after-statement -Wno-unused-but-set-variable -Wno-unused-local-typedefs -DNDEBUG -nostdinc -fno-builtin -fno-common -Werror -Wredundant-decls -Wno-pointer-arith -pipe -g -D__XEN__ -include /home/thomas/projets/buildroot/output/build/xen-4.7.0/xen/include/xen/config.h '-D__OBJECT_FILE__="asm-offsets.s"' -Wa,--strip-local-absolute -MMD -MF ./.asm-offsets.s.d -mcpu=generic -mgeneral-regs-only -I/home/thomas/projets/buildroot/output/build/xen-4.7.0/xen/include -fno-stack-protector -fno-exceptions -Wnested-externs -DGCC_HAS_VISIBILITY_ATTRIBUTE -S -o asm-offsets.s arm64/asm-offsets.c
>
> And the build succeeds.
>
> So apparently, the fact that we are passing our own CFLAGS confuses the
> Xen build system, which then adds its own CFLAGS twice for some reason.

That is exactly what I see as well.

It was surprising to me as well, but the only way I could figure out
how to fix this build issue was to remove the flags.

Is this an acceptable solution, or do I need to look at the Xen build
system and patch that to not add the duplicate options?

Thanks,

Alistair

>
> Thomas
> --
> Thomas Petazzoni, CTO, Free Electrons
> Embedded Linux and Kernel engineering
> http://free-electrons.com
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