[PATCH kernel v2] powerpc/makefile: Do not redefine $(CPP) for preprocessor

[Alexey Kardashevskiy]

On 11 May 2021 21:24:55 Segher Boessenkool <segher at kernel.crashing.org> wrote:

> Hi!
>
> On Tue, May 11, 2021 at 02:48:12PM +1000, Alexey Kardashevskiy wrote:
>> --- a/arch/powerpc/kernel/vdso32/Makefile
>> +++ b/arch/powerpc/kernel/vdso32/Makefile
>> @@ -44,7 +44,7 @@ asflags-y := -D__VDSO32__ -s
>>
>> obj-y += vdso32_wrapper.o
>> targets += vdso32.lds
>> -CPPFLAGS_vdso32.lds += -P -C -Upowerpc
>> +CPPFLAGS_vdso32.lds += -C
>>
>> # link rule for the .so file, .lds has to be first
>> $(obj)/vdso32.so.dbg: $(src)/vdso32.lds $(obj-vdso32) 
>> $(obj)/vgettimeofday.o FORCE
>
>> --- a/arch/powerpc/kernel/vdso64/Makefile
>> +++ b/arch/powerpc/kernel/vdso64/Makefile
>> @@ -30,7 +30,7 @@ ccflags-y := -shared -fno-common -fno-builtin -nostdlib \
>> asflags-y := -D__VDSO64__ -s
>>
>> targets += vdso64.lds
>> -CPPFLAGS_vdso64.lds += -P -C -U$(ARCH)
>> +CPPFLAGS_vdso64.lds += -C
>>
>> # link rule for the .so file, .lds has to be first
>> $(obj)/vdso64.so.dbg: $(src)/vdso64.lds $(obj-vdso64) 
>> $(obj)/vgettimeofday.o FORCE
>
> Why are you removing -P and -Upowerpc here?  "powerpc" is a predefined
> macro on powerpc-linux (no underscores or anything, just the bareword).
> This is historical, like "unix" and "linux".  If you use the C
> preprocessor for things that are not C code (like the kernel does here)
> you need to undefine these macros, if anything in the files you run
> through the preprocessor contains those words, or funny / strange / bad
> things will happen.  Presumably at some time in the past it did contain
> "powerpc" somewhere.
>
> -P is to inhibit line number output.  Whatever consumes the
> preprocessor output will have to handle line directives if you remove
> this flag.  Did you check if this will work for everything that uses
> $(CPP)?

i don't know about everything for sure but i checked few configs and in all 
cases (except vdso) $CPP was receiving cflags.

>
> In any case, please mention the reasoning (and the fact that you are
> removing these flags!) in the commit message.  Thanks!


but i did mention this, the last paragraph... they are duplicated.

>
>
> Segher

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