User Extensions, TCB Extension area, and TCBs in general

[Wu, Mark H.]

Thank you. I'll give that a try.


-----Original Message-----
From: Sebastian Huber [mailto:sebastian.huber at embedded-brains.de] 
Sent: Tuesday, May 19, 2015 00:34
To: Wu, Mark H.
Cc: users at rtems.org
Subject: Re: User Extensions, TCB Extension area, and TCBs in general



On 18/05/15 21:47, Wu, Mark H. wrote:
> -----Original Message-----
> From: Sebastian Huber [mailto:sebastian.huber at embedded-brains.de]
> Sent: Monday, May 18, 2015 11:49
> To: Wu, Mark H.
> Cc:users at rtems.org
> Subject: RE: User Extensions, TCB Extension area, and TCBs in general
>
> Hello Mark,
>
> which RTEMS version do you use?  The fatal extension changed considerably between 4.10 and the master.
>
> ----- Wu, Mark H.<Mark.H.Wu at disney.com>  schrieb:
>> >I guess I'm a little confused, then. I want to install a global fatal exception handler at configuration time, and I would like to enable the stack bounds checker. But I would also like to add other extensions in addition to those. So what I'm wondering is:
>> >
>> >1. Will enabling the stack bounds check overwrite the fatal exception handler?
>> >2. Will my extension set overwrite the stack bounds check?
>> >3. If the answer to those questions is "yes," then how do I work around it?
> You can have as many initial extensions as you like, they are installed via a read-only table in confdefs.h.  A global fata exception handler is a typical use case for this, see also test sptests/spfatal26.  One limitation is that you have no data field for initial extensions in the TCB.  With the support for thread-local storage, this is not really a problem.
>
> But how does the stack bounds check interact with the initial extensions? Or are they incorporated into the initial extensions at configuration time? I still need a way to call-back the stack bounds check functions if I need to augment one or more of the extension functions, so I still need a way to "retrieve" its pointer from the current set.
>

The stack checker is an initial extension. If you need more control, 
then you can also call the stack checker functions in your own 
extension, see. stackchk.h.

-- 
Sebastian Huber, embedded brains GmbH

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