Jeremy Fitzhardinge wrote:

Ingo Molnar wrote:
  

quoted

why not vmalloc it on the guest side? fixmaps are bad for this purpose 
for a general paravirt implementation, it limits the size of the shared 
info page, etc.
    

Yes.  vmalloc would have the annoying side-effect of actually allocating
some pages which would be shadowed by the remapping, but I guess
get_vm_area would do the job.  I'll give it a go.

Hm, this is a bit awkward.  We need to map the shared info page fairly
early - say, around paging_init - but we're still on the bootmem
allocator at that point, so get_vm_area isn't usable yet.  Using a
fixmap keeps things simple.  It seems to me that having a single fixmap
available is useful for this kind of simple/early mapping, and if
someone needs to map something larger, then they can put it off until
get_vm_area() is available...

    J