Re: [MiNT] Fpoll() in GEM programs

[Frank Naumann <fnaumann@cs.uni-magdeburg.de>]

Hello!

> Is it possible for the AES to create a file descriptor, and set the current 
> process id as the owner of this file descriptor ?

The kernel don't manage the resources in this way. Every process have it's 
own, private file descriptor table. But how does a process know what the 
AES provide this feature and how does the process know which is the right 
descriptor?

> I never talked about pipe. I only talked about the generic "file descriptor" 
> term, because it cover lot of things.

You know that there must be some code behind this file descriptor?

> Ok... i'll once more try to argument on a subject i don't know very well... 
> BTW, if i correctly understand, we cannot create a file descriptor. We can 
> create a file and the function returns a filedescriptor. We can create a pipe 
> and the function returns a fd. We can create a socket and the function 
> returns a file descriptor... a "file description" is a generic handle that 
> may hide a lot of very different things, and i'm not sure that pipe is the 
> good type for our need.

So you need to introduce a new type.

> There's nothing magic. We can read/write stuff to this file descriptor (if 
> needed), but only AES functions has to do it.

There are lot of other things you are probably not aware yet. A file 
descriptor is more than just a read/write/select interacting resource:

- A file descriptor is an elementar resource a process
  can create/modify/destroy
- A file descriptor is inherited by child processes
- A file descriptor is duplicateable
- A file descriptor is manipulable in various ways:
  - setting/getting attributes
  - modifying behaviour
- A file descriptor support fstat, fchown, fchmod and such things

> exceptfds
> This set is watched for exceptions or errors on any of the file descriptors. 
> However, that is actually just a rumor. How you use exceptfds is to watch for 
> Out of Bounds (OOB) data. OOB data is data sent on a socket using the MSG_OOB 
> flag, and hence exceptfds only really applies to sockets(...)
> "
>
> This feature may be used, no ?

So you want to use the error exception event to notify about regular AES 
events? Funny ...

> The AES writes stuff to itself, and read stuff 
> from itself, using OOB data; i don't see any magical thing here.

I don't understand. Until know you said the AES inform the process about 
new AES events through a file descriptor.


Regards,
Frank

--
ATARI FALCON 060 // MILAN 060
-----------------------------------------
http://www.cs.uni-magdeburg.de/~fnaumann/
e-Mail: fnaumann@freemint.de