[ECOS] RE: Reentrancy of the ecos drivers

harbonne marc marc.harbonne@silicomp.fr
Tue Jul 18 14:39:00 GMT 2006


The driver I speak about is the ipaq touch screen present under
/devs/touch/ipaq but my remark concerns also the i82559 ethernet driveror
any other driver, so If I understand it is the responsibility  of the
developer to make its own protection if he wants to share the same resource
between two or more tasks ?
It means that theses drivers are not re-entrant ?

Regards
Marc 

-----Message d'origine-----
De : Gary Thomas [mailto:gary@mlbassoc.com] 
Envoyé : mardi 18 juillet 2006 14:26
À : harbonne marc
Cc : ecos-discuss@ecos.sourceware.org
Objet : Re: [ECOS] RE: Reentrancy of the ecos drivers

harbonne marc wrote:
> 
> 
> Hi all,
> 
>  
> 
> My question is quite general, I cannot see in any ecos drivers provided
with
> the last version of ecos, a way to protect the shared resources.
> 
>  
> 
> As example, if you look at any display driver, we cannot see a semaphore
> that will protect from a second task to access to the resource by
> pre-empting the one which has the resource.
> 
>  
> 
> The only call I can see is a cyg_scheduler_lock and unlock to get/release
> the resource.
> 
>  
> 
> But in many drivers such mechanism does not exist.
> 
> Can you tell me why?

In most cases, such resource management (if it's required) is handled
at a level higher than the physical device driver.

What driver(s) are you concerned about?

-- 
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
------------------------------------------------------------


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