On Mon, 2009-11-09 at 14:37 +0100, Philippe Gerum wrote: > 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.
Forget about this one, this does not apply to x86 anymore. So the answer to this question is rather: that used to be required on x86 a long time ago due to the implementation of the task switching code in system.h (2.4 era IIRC); but in any case, yes, this is still required for the reasons explained above, since we must run the switch code with hw IRQs off. > > > > > Jan > > > > -- Philippe. _______________________________________________ Adeos-main mailing list [email protected] https://mail.gna.org/listinfo/adeos-main
