Re: [ECOS] Scheduler startup question

[Michael Jones <mjones@linear.com>]

By tracing through a Cortex M application that works, I found that when the first thread is run, there is a loop at the bottom of the thread entry call that calls unlock until sched_lock is 0. Every thread entry does this.

This seems a bit dangerous to me, as the unlocking occurs anytime a new thread is created. I have to assume that the thread could not be entered when in a critical section between scheduler locks.

I'll look into that behavior and see if it is related to my BSD assertion.



On Feb 26, 2014, at 11:40 PM, Lambrecht Jürgen <J.Lambrecht@TELEVIC.com> wrote:

> As far as I know the scheduler is started after cyg_user_start(), used by your application to initialize everything.  Do you use cyg_user_start?
> 
> 
> Verzonden vanaf Samsung Mobile
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> 
> -------- Oorspronkelijk bericht --------
> Van: Michael Jones <mjones@linear.com>
> Datum:
> Aan: ecos discuss <ecos-discuss@sourceware.org>
> Onderwerp: [ECOS] Scheduler startup question
> 
> 
> I have a question about proper scheduler locking startup behavior.
> 
> The context is I am cleaning up my iMX6 HAL and attempting to make things work without a couple of kernel hacks I added to make it work.
> 
> The question has to do with sched_lock. By default this has a value of 1, so during startup the scheduler is locked.
> 
> When there is an interrupt, sched_lock is incremented in Vectors.S, and decremented in interrupt_end.
> 
> However, I am getting an assert in sync.h which is part of the BSD stack. The assert is because it expects the lock to be zero.
> 
> The question is, during the startup process, how does the lock get set to zero after initialization? Is it supposed to stay 1 while hardware is initialized and through all the constructors, etc? Is it cleared by the scheduler somehow? Is the HAL supposed to zero it at some point during startup?
> 
> My HAL is part of the ARM hal, so if this is device specific, it is the ARM HAL I am working with.
> 
> Mike
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