realmode _WAKEUP

[Alexander Kuleshov]

8 янв. 2015 г. 0:57 пользователь "Paul Bolle" <pebolle at tiscali.nl> написал:
>
> On Wed, 2015-01-07 at 23:59 +0600, Alexander Kuleshov wrote:
> > 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?
>
> Because these file also get compiled via arch/x86/boot/Makefile? Ie, I
> _guess_ _WAKEUP is needed to ensure the compile started from
> arch/x86/realmode/rm/Makefile differs from the compile started from
> arch/x86/boot/Makefile. But [...]/boot/Makefile is sufficiently
> complicated for me to stop me from looking at it too long!
>
> You do realize that the Linux kernel is a treasure trove for people
> wanting to know just how far make, gcc, etc can be pushed, don't you?
>
>
> Paul Bolle
>

That's true
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