In some email I received from matthew green, sie wrote:
>    
>    Modified Files:
>    	syssrc/sys/arch/sparc/sparc: iommu.c
>    
>    Log Message:
>    fix so it compiles on a system without 'options SUN4M'
> 
> 
> hmm... not sure this is really the right fix.
> 
> 
> having iommu support without sun4m support is extra weight
> you can't use.  the right fix seems to be to avoid compiling
> iommu.c entirely if !SUN4M...

Yes, I noticed this after the commit, which made me wonder why
there were any #ifdef's for SUN4M in that file at all...