Re: [Xenomai-help] Xenomai VxWorks Skin--->semTake

[Philippe Gerum <rpm@xenomai.org>]

On Wed, 2011-08-03 at 16:30 +0200, Sambasiva Rao Manchili wrote:
> Hi Philippe,
> Why do you say that I try to grab the mutex from non-xenomai thread
> context ?

Because this is what you are very likely doing. Calling a Xenomai-only
service over a non-Xenomai thread.

> During porting we had written main() only this main function does
> pthread_create to call the very first function of VxWorks code which
> inturn does taskSpawn. All the taskSpawns has to go through Xenomai
> thread context right ?

Task created by taskSpawn() are valid Xenomai context for sure. main()
is not by default.

I can't check your code, but EPERM is typical of calling a resource
grabbing service out of a valid Xenomai context. Xenomai can't move your
calling context to primary mode before executing this service and fails
early with EPERM. 

>  
> Samba.
>  
>  
> -----Original Message-----
> From: Philippe Gerum [mailto:rpm@xenomai.org] 
> Sent: Wednesday, 03. August, 2011 15:53
> To: Sambasiva Rao Manchili
> Cc: Gilles Chanteperdrix; Antonio Gambin; Xenomai-help@domain.hid
> Subject: RE: [Xenomai-help] Xenomai VxWorks Skin--->semTake
>  
> On Wed, 2011-08-03 at 15:31 +0200, Sambasiva Rao Manchili wrote:
> > Hi Gilles,
> > I had seen the code  in src\skins\vxworks\semLib.c it returns ERROR
> which is -1.
> > 
> > The value that I sent earlier is the value that I got out of the
> following statement.
> > serrLog( serrErr,
> >              "resu_getonline_1_svc: semTake for restab_access_smp
> failed!!<%s>",
> >               strerror(errnoGet()));
> > 
> > Is it right ?
> > 
> > 
> > Now again I tried with
> >  serrLog( serrErr,
> >              "resu_getonline_1_svc: semTake for restab_access_smp
> failed!!<%s> <%d>",
> >               strerror(errnoGet()), errno);
> > 
> > Here I get value 1 for errno.
>  
> You are trying to grab the mutex from a non-Xenomai thread context.
> This is invalid.
>  
> > 
> > Samba.
> > -----Original Message-----
> > From: Gilles Chanteperdrix [mailto:gilles.chanteperdrix@xenomai.org]
> > Sent: Wednesday, 03. August, 2011 15:18
> > To: Sambasiva Rao Manchili
> > Cc: Philippe Gerum; Antonio Gambin; Xenomai-help@domain.hid
> > Subject: Re: [Xenomai-help] Xenomai VxWorks Skin--->semTake
> > 
> > On 08/03/2011 02:44 PM, Sambasiva Rao Manchili wrote:
> > > Hi Philppe,
> > > Failed and return with error code is  <Unknown error 4294967295>
> and continues. I do not know the granularity of time  here, if it is
> returning immediately or not.
> > > We have about 15 tasks spawned in this whole system. Done very
> very minimal changes to our VxWorks code to run on Linux over Xenomai
> version 2.5.6.   Board does not crash.
> > > CPU Platform is Intel x86 Arch 32 Bit.
> > 
> > semTake does not return error code directly, it returns ERROR (which
> is -1, or 4294967295 if you cast to unsigned), and the real error is
> in the errno variable.
> > 
> > --
> >                                             Gilles.
> > 
> > 
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>  
> --
> Philippe.
>  
>  
>  
> 
> 
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-- 
Philippe.