> I would like to use UVM to allocate large memory in kernel land.  I
> used uao_create, round_page, uvm_map to allocate virtual space.

As I understand it, those allocate userland VM.

> But now I would like to write and read inside those pages still being
> in kernel land.  When I tried with copyout to write buffer inside it
> I got a page fault...

I don't recall what process your code is creating userland memory for.
If it's not the current process - the one in curproc - or something
suitably similar for a multiprocessor kernel, copyout won't work.

> I learnt from der Mouse that at this step no backend physical pages
> are created in relation to my virtual space, how do I have to force a
> page creation?

If the memory is for the current process, I _think_ copyout should do
that.

Of course, I could be wrong.

It sounds to me as though what you really want is pageable kernel
memory.  I don't know whether that exists at present.

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