On Thu, May 20, 2021 at 08:53:34PM +0200, Volker Rümelin wrote:
> > On Fri, May 14, 2021 at 08:03:20PM +0200, Volker Rümelin wrote:
> > > The comment above the yield() function suggests that yield()
> > > allows interrupts for a short time. Currently this is only true
> > > if seabios was built without CONFIG_THREADS or if yield() is
> > > called from the main thread. Change the code to always call
> > > check_irqs() in yield().
> > I'm confused about the failure scenario you describe here, as yield()
> > really should always allow irqs to run prior to returning. When
> > called from a "background thread" it will not directly enable irqs,
> > but it will always cycle through all "threads" before returning. Thus
> > the "main thread" should always be reached and when it runs yield() it
> > will permit irqs to run.
> >
> > Am I missing something?
>
> Hi Kevin,
>
> the main thread calls run_thread() to create a background thread, adds it
> behind main thread in the thread list and immediately executes the
> background thread until the background thread calls yield(). All background
> threads in the thread list run in sequence and call yield() until the last
> background thread yields to main thread. The main thread has not reached
> wait_threads(), which means it will create another background thread and run
> it. This will repeat until all background threads are created. You can see
> until now the main thread did not call yield() but the background threads
> ran several times. The main thread calls yield() for the first time in
> wait_threads().
Thanks. It does seem the code is not doing what was intended. Could
we add the check to the bottom of run_thread() though? Something
like:
if (cur == &MainThread)
// Permit irqs to fire
check_irqs();
-Kevin
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