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Re: [Fwd: Re: Deva interface]

From: R. Koot
Subject: Re: [Fwd: Re: Deva interface]
Date: Thu, 20 Jan 2005 19:24:34 +0100
User-agent: Mozilla Thunderbird 1.0 (X11/20041206)

markus kaarn wrote:
Marcus Brinkmann wrote:
 >  Does anybody else see other problems with making Deva a library?

If you define Deva as a library, what do you profit ?
Deva, as server, can serve at least as place for registering
device drivers. If client needs to access a device, he goes
for Deva and asks, if there is one he needs.

There is still, must be a place to keep device-list register.
If Deva will not serve as one. Another place will be created.
Do we really must dual the work?

On any micro-kernel based OS you will need some kind of Name Service to find other services. (Task will do this in HURD, correct me if I'm wrong). This service can also manage the "device list". So you by not letting Deva do it you actually avoiding double work. Another way to find devices if by querying the root driver which will return a list of bus drivers wich in turn return a list of device drivers.

If every time, i start my program and Deva-library with it. LibDeva will
have to lookup though the system-services(whatever) to find device-drivers
or plugin-managers to be used by my program. This will result in more
code execution.

Looking up a device in the nameserver will be just as slow as lokking it up in a "Deva-server". And the servers that access drivers directly will be servers that are started once during boot, because they are the servers that abstract devices into more useable things (think a windowing system, LVM, audio service, ... )

On other hand, there will still be work involved between deva and ddf,
and proper interfaces between them (as i know) have to be worked out.

We must see both cases in action, so can compare? %')

I'm seeing Deva as a collection of servers, libraries adn protocols. Now if you can logically deduce that the operations performed by this is a subset of the operations performed by "Deva as a server" you will be certain it will perform equal of better in the real world, so you don't need a proof-of-concept for both.


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