Re: MADO and Graphics

[David Jeske <jeske@home.chat.net> writes:]

>Andy: if a server setup a shared memory segment on 'physically mapped
>pages', and then a client connects to it, is it currently possible for
>the server to change the physical pages that shared memory segment
>maps to after the fact?

Hmmm, not really, since there's not (currently) any good way to name a
shared object distinct from naming what it maps. I think it'd require a new
page set (struct pset, psop_* stuff) object type. In fact, I think it would
have to be a lot like a ZFOD set, with an operation to switch from the
backing store memory set to a physical map set.

>I believe this would be required for GGI to work, because the server
>needs to be able to switch the client mapping from the 'real
>framebuffer' to a 'backing store' without the client knowing about it.

Delta some interesting race conditions. Switching the mapping of the page
set isn't enough, because you also have to hammer the client's PTE's and TLB
(if they're running when you do the switch). I think some of the current
page stealing code would have to be generalized to support this.

I'll do the VM work if somebody actually wants to try a GGI port!

                                                                Andy
Received on Sat Oct 3 09:47:46 1998