SEO

Michael Shalayeff wrote:
> that's not what submaps are made for.
> also since you would require some sort of allocator to be written
> anyway what is the difference wrt using shmems anyway?
>
[ -- cut -- ]
> also. what NEEDS a contiguos virtual space for later
> split in smaller allocs. what is the application is
> that you require this for?

For the most part, this is an academic exercise.

> why not use mmap() ?

Basically, I want a vm_map_entry covering an address region to be able
to ultimately point to a vmspace (and thus, a vm_map), which then can be
shared with another process.

Like what happens now in uvmspace_share() for rfork(), except that in
this case, I don't want to share the entire VM space, but a possibly
large portion of it that may or may not have gaps in them (i.e. may not
be filled up with allocated pages)

Think of the application as a monitor for virtual memory, which also
needs direct access to the memory region.
In other words, All this has to be transparent with respect to the
client, but ptrace() by itself is not an option (for now).

The client process will be using mmap()/shmat() for other things (like
allocating pages for use within the shared subspace) - and I want all vm
operations in the given VM subspace (map,unmap, etc..) to be "auditable"
as well as direct access to the contents of the memory itself.

In the end, however, the original question still stands -
Before getting out the work-clothes for an extended uvm hacking session,
I thought I'd ask for advice/hints..

So, how difficult would it be to subvert the submap mechanism for this
purpose? If anyone has advice/hints to give, I'd appreciate it very much.


Thanks,
-Jason Kim