Problems with the blackfin port

Allan Hessenflow allanh-rtems2 at
Tue Apr 1 17:58:02 UTC 2008

Joel Sherrill wrote:
> self-nesting?  Is this "restoring the interrupt disable
> level to that of the task"?

In this context self-nesting is a Blackfin specific term.  It means
that an interrupt of a given priority can interrupt another of the same

> The context switch code is supposed to include interrupt
> disable level per task.  

Yes, the Blackfin code does that.  However, the whole approach of using
a software interrupt to do the thread dispatch relies on the lowest
priority interrupt being enabled at any time that any other interrupt
is also enabled.  That requirement is currently met by the port only
supporting two levels, all enabled and all disabled.  If it were to be
expanded to support multiple levels, it could still be met by just
insuring the lowest priority level is enabled for all but the case
where all other levels are disabled.


Allan N. Hessenflow      allanh at

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