On Mon, 2009-11-09 at 14:00 +0100, Jan Kiszka wrote:
> Hi Philippe,
> 
> a customer just stumbled over some unclear spots in current I-pipe patches:
> 
> Why is there local_irq_enable_hw in task_hijacked? Looks like it was
> once paired with prepare_arch_switch, but that call is now only used by
> legacy 2.4 PPC.

It is still used in all trees, since we define it in asm/ipipe.h. We
could not context switch properly on the linux side with hw interrupts
on anyway, due to the conflicts that would raise with Xenomai's tasking
code.

>  Can we safely drop it from all other patches (it's in
> the context switch fast-path...)?

No, since prepare_arch_switch() is still applicable.

>  Moreover, I bet the
> ENABLE_INTERRUPTS_HW_COND in entry_32.S' ret_from_fork is related to
> this as well, right?

No, it's there to prevent the scheduling tail from running hw IRQs off,
given that copy_thread() may set a copy for eflags which prevents
preemption.

> 
> Jan
> 


-- 
Philippe.



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