Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!usc!pollux.usc.edu!papa
From: papa@pollux.usc.edu (Marco Papa)
Newsgroups: comp.sys.amiga.tech
Subject: Re: resource tracking
Keywords: Discipline, discipline
Message-ID: <22973@usc.edu>
Date: 20 Feb 90 06:03:18 GMT
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In article <5185@sugar.hackercorp.com> peter@sugar.hackercorp.com (Peter da Silva) writes:
>In article <22955@usc.edu> papa@pollux.usc.edu (Marco Papa) writes:
>> Well, on the Amiga ALL system calls are done through libraries. Name me
>> one system call in graphics.library that is a "message".
>
>I don't think there's anything in graphics.library that's a system call. A
>shared library is a great thing, but it's still a shared library. It executes
>in the context (and the ownership) of the task currently executing. To
>actually do I/O, and in particular to perform input, you have to send messages
>around.

I guess we have different ideas of what a "system" call is.  Is writing to
the screen "doing I/O"? I think so. I call it OUTPUT :-) You don't seem to 
think that . UNIX, to take the example from which you've derived the use of 
"system calls", has open, close, read, write and ioctl (and mods of that).  
To write to the display on UNIX, you'd probably
end up doing read/writes and a bunch of adapter specific ioctls. Are those
system calls? I thinks so.  On the Amiga, to do the same you call routines
in graphics.library (or layer.library). As far as I know, these don't involve
message passing of any kind. They invoke ROM kernel routines directly (pretty
much like an adapter/specific ioctl would do). Are these "system" calls?
I think so. You don't.  Who cares?  Look at the Amiga System Software modules
picture in the RKMs. Graphics, audio, keyboard, mouse, etc. all talk directly
to the hardware. None of their specific system calls for DOING I/O (most of 
them in ROM, since some of these libraries are ROM libraries, and they are 
just the same as adapter firmware or microcode on differernt platforms) 
involve message passing.  So IMHO, the statement that "all system calls in 
the Amiga involve message passing is pure b.s.".

The discussion is stale (i.e "what is the meaning of system call?"). Next 
topic, please.

Have fun and enjoy the universe.

-- Marco
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