> > we can easily tweak the api.
> 
> This would mean changing all device's mmap functions, isn't ?

or introduce optional d_foo entry points.
for the purpose of udv_attach, it's a little silly to call a driver for
every single page frames.

as foreign pages can't be represented by paddr_t, some tricks are
necessary for d_mmap+pmap_enter in udv_fault.

> I'd prefer to see support for custom mmap in /kern ...

why?

> Now that I'm thinking about it, it should be possible to create a
> uvm_object backed mapping in the ioctl calls, isn't it ?

you can, but i think it's better to actually implement mmap.

YAMAMOTO Takashi