Re: UIO - interrupt performance

[Marco Stornelli <marco.stornelli@coritel.it>]

No I don't think you can decide kernel or user space, indeed you can
read my previous posts, I quite agree with you, I meant the same to Bill
Gatliff.

Ben Nizette ha scritto:
> On Tue, 2008-10-21 at 11:30 +0200, Marco Stornelli wrote:
>> I could agree, but "the facto" due to UIO license condition, a company
>> often uses UIO drivers, regardless performance, debug, etc, only as not
>> to public the code under GPL.
> 
> It sounds to me like you think that driver authors can sit down and
> decide whether they want to implement their driver in userspace or
> kernel space.  For 99% of drivers that's simply not true.  You  *cannot*
> write userspace drivers for most hardware, the hooks just aren't
> available.  UIO is Userspace I/O, not a set of general hooks for
> userspace drivers.
> 
> If people want drivers not under the GPL then they can distribute a
> binary-only module (though thank $DEITY there aren't many of those
> left).  Userspace I/O exists to provide good performance interfacing to
> a family of devices - those which exist just to shuffle data around and
> have an interrupt to tell you when they're done.
> 
> Do you have any example of a userspace i/o driver which exists to get
> around licencing constraints?
> 
> 	--Ben.
> 
> 

-- 
Marco Stornelli
Embedded Software Engineer
CoRiTeL - Consorzio di Ricerca sulle Telecomunicazioni
http://www.coritel.it

marco.stornelli@coritel.it
+39 06 72582838