> Yes, so we have to keep a translation table, with an ioctl to populate it.
> Then we have to change xen sources to deal with it, and it may not be so
> easy because what it does now is the other way round: first get a
> chunk of VM space, and then populate it, eventually not in one operation.

iirc we used to mmap privcmd to allocate va range.
it was better than overwriting unrelated mappings as we currently do.
(imo, the use of kernfs was a mistake and privcmd should be a normal device.)

YAMAMOTO Takashi