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Re: New thoughts about deva/fabrica

From: Peter 'p2' De Schrijver
Subject: Re: New thoughts about deva/fabrica
Date: Sat, 20 Aug 2005 16:03:16 +0200
User-agent: Mutt/1.5.6+20040907i

> > Third, if u have a look at "conventional" drivers, there's no or very 
> > less need of libc functions.
> That's because they're not allowed to be used from there. ;-)  I would add a
> network server to my Linux device drivers for debugging or controlling if I'd
> be allowed by Linux.  But I'm not, so I don't use all the libc calls for
> networking.  I don't have a real idea of what I'd use if everything was
> allowed, but I think it would be quite a lot.

I don't think libc calls are very useful in drivers. libc basically
offers stream based I/O which is useless for drivers as they generally
work with packets, memory management which is too crude (drivers need to
be able to ask for pinneable memory, memory in certain physical address
range for DMA, etc...), string functions which are useless for drivers
(drivers don't interpret data, they mostly pass data around without looking at 
it), memcpy etc which is somewhat useful but very easy to implement in a small 
library, math functions which are mostly useless as drivers don't need
much more then very basic arithmetics. Drivers generally don't offer
posix interfaces because the hardware they abstract is very far from
posix semantics.


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