[directfb-dev] Re: Can I get some advice and clarification?

[Chad Hardin <cehardin@mac.com>]

On Dec 18, 2003, at 2:57 AM, Denis Oliver Kropp wrote:

> Quoting Chad Hardin:
> > I've been itching to make the SimplyGNUstep distro use something other 
> > than XFree86 for a long time now.
> >
> > As far as I can see, there are two ways I can go about this by using 
> > directfb.
> >
> > 1.  Use fusion, every GNUstep app will be a directfb app.  The problem 
> > with this is that AFACT fusion is a cooperative resource locking 
> > scheme, is that the case?  If so, I don't think it would be appropriate 
> > for use in a desktop environment, especially with a sub-1.0 release of 
> > gnustep-gui and an beta backend.  Hopefully I'm wrong about it being 
> > cooperative based.
>
> What do you mean by "cooperative resource locking"?
>
> There are global locks for global resources, but these locks are only
> held as long as the core function that requires it is running.

Ahh, so the likelihood of stale locks are small to none then?


> > 2.  Create a lightweight window manager which uses directfb in single 
> > app mode.  this would be a client/server approach where the server and 
> > each app have shared memory regions, which the apps draws to and the 
> > window server then blits to the screen.
>
> This wouldn't make any sense, you'll loose all benefits of DirectFB.

I know!  that is why I'm asking these questions!  :-)

> > I think option 1 would be much easier to implement than option 2, so I 
> > would prefer to lean in that direction.  But, the cooperative resource 
> > locking thing makes me a bit nervous.
> >
> > so my biggest question is:  Is fusion really cooperative based locking? 
> > If so, how likely is that to cause problems for applications which 
> > hang while locking?  And, what are the plans for fusion in the future, 
> > can I expect any significant changes?  I noticed that there was maximum 
> > amount of 8 (or so) simultaneous clients (8 device nodes), will this be 
> > changed so that this number is higher (much higher)?
>
> There are no clients, but "fusionees", one is the master, others are slaves.
> The number of fusionees is unlimited. Each device node is a fully separate
> "session" or "world". Usually you have one session, sometimes two. The number
> of sessions can be compared with the number of X servers you would run.


Has this been a recent change?  I remember the last time I tried fusion there was a limit of only 8 device nodes.

I'm thinking I must have misunderstood what these device nodes where used for.  I was under the impression that every client needed it's own device node!

If that is indeed the case then I'm gonna start planning for a new directfb backend for gnustep.  You may remember I made the objective-c bridge for DirectFB a while back.  the whole purpose of that was to make the creation of a DirectFB backend easier.

Chad


> -- 
> Best regards,
> Denis Oliver Kropp
>
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