vga16fb doesn't build on powerpc (vgacon_remap_base)

[Geert Uytterhoeven]

On Tue, 16 Oct 2007, Joseph Fannin wrote:
> vga16fb is an available config option on powerpc, but it won't link
> with my .config:
> 
>     ERROR: "vgacon_remap_base" [drivers/video/vga16fb.ko] undefined!
> 
> 
> I'm guessing this is because include/asm-powerpc/vga.h declares
> vgacon_remap_base: 
> 
>     extern unsigned long vgacon_remap_base;
> 
> 
> ...but arch/powerpc/kernel/setup_32.c wraps the definition in an #ifdef:
> 
>     #ifdef CONFIG_VGA_CONSOLE
>     unsigned long vgacon_remap_base;
>     EXPORT_SYMBOL(vgacon_remap_base);
>     #endif
> 
> 
> So CONFIG_VGA_CONSOLE=n and CONFIG_FB_VGA16=[y|m] won't work.
> 
> I've also noticed that the only places in the tree that ever assign
> anything to config_remap_base are under arch/ppc.  And
> include/asm-powerpc/vga.h also does this:
> 
>     #ifdef __powerpc64__
>     #define VGA_MAP_MEM(x,s) ((unsigned long) ioremap((x), s))
>     #else
>     #define VGA_MAP_MEM(x,s) (x + vgacon_remap_base)
>     #endif
> 
> 
> So VGACON probably doesn't work either on 32bit.  I'm guessing arch/powerpc
> doesn't support PREP.

It's not only useful for PREP, but also for CHRP.

> How best could this be fixed up? Or should I just let the thing
> be?  This is obviously not a new thing, and I don't have any hardware
> that supports this stuff either.

I remember this problem was present when I still had a working LongTrail (which
is CHRP), long before arch/powerpc/ was created.

With kind regards,
 
Geert Uytterhoeven
Software Architect

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