realmode _WAKEUP

[Alexander Kuleshov]

Hello Paul, thank you for answer.

Yes i saw video-*.c files, but i can't understand how compilation of
these video-*.c files depends on _WAKEUP macro...

For example if'd remove -D_WAKEUP, i get errors during realmode.elf linking:

arch/x86/realmode/rm/video-vga.o: In function `vga_probe':
/home/alex/dev/linux/arch/x86/realmode/rm/../../boot/video-vga.c:259:
undefined reference to `boot_params'

As you wrote there are many #ifndef/#endif directives, but why there
_WAKEUP is undefined everytime, but we pass it from command line with
-D_WAKEUP?

Thank you.

2015-01-07 22:54 GMT+06:00 Paul Bolle <pebolle at tiscali.nl>:
> On Wed, 2015-01-07 at 20:12 +0600, Alexander Kuleshov wrote:
>> There is following definition at arch/x86/realmode/rm/Makefile:
>>
>> KBUILD_CFLAGS    := $(LINUXINCLUDE) $(REALMODE_CFLAGS) -D_SETUP -D_WAKEUP \
>>            -I$(srctree)/arch/x86/boot
>>
>> Is it used now? I'm asking because _WAKEUP definition everywhere
>> undefined in the code.
>
> git grep tells me:
>     $ git grep -n "_WAKEUP\b" arch/x86
>     arch/x86/boot/video-bios.c:51:#ifndef _WAKEUP
>     arch/x86/boot/video-bios.c:66:#ifdef _WAKEUP
>     arch/x86/boot/video-mode.c:169:#ifndef _WAKEUP
>     arch/x86/boot/video-vesa.c:27:#ifndef _WAKEUP
>     arch/x86/boot/video-vesa.c:29:#else /* _WAKEUP */
>     arch/x86/boot/video-vesa.c:31:#endif /* _WAKEUP */
>     arch/x86/boot/video-vesa.c:160:#ifndef _WAKEUP
>     arch/x86/boot/video-vesa.c:272:#endif /* not _WAKEUP */
>     arch/x86/boot/video-vga.c:257:#ifndef _WAKEUP
>     arch/x86/boot/video-vga.c:269:#ifndef _WAKEUP
>
> And in that Makefile we also see, a few lines up:
>     wakeup-objs     := [...] video-mode.o
>     [...]
>     wakeup-objs     += video-vga.o
>     wakeup-objs     += video-vesa.o
>     wakeup-objs     += video-bios.o
>
> So this Makefile line defines a _WAKEUP macro that is, it seems, used
> for the build of those four object files. (It's bit more complicated
> than that. But I think KBUILD_CFLAGS is explained in Documentation/,
> isn't it?)
>
> Hope this helps,
>
>
> Paul Bolle
>



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