when to mark reserved low memory pages

[John Rose]

We have a need to mark a certain range of low memory (alloc_bootmem)
pages as reserved, similar to the way that kernel pages are marked
reserved in mem_init().  The region is question is rtas_rmo_buf, if
you're curious.  

So would mem_init() be the appropriate place to do this, and if so,
should it also be done in the CONFIG_DISCONTIG case?

Thanks-
John 
Memory Mgmt. Ignoramus