Messages in this thread | | | Date | Tue, 26 Jul 2005 14:00:15 +0200 | From | Ingo Molnar <> | Subject | Re: 2.6.12 PREEMPT_RT && PPC |
| |
* john cooper <john.cooper@timesys.com> wrote:
> Ingo, > Attached is a patch for 51-28 which brings PPC up to date for > 2.6.12 PREEMPT_RT. My goal was to get a more recent vintage of this > work building and minimally booting for PPC. Yet this has been stable > even under our internal stress tests. We now have this running on > 8560 and 8260 PPC targets with a few others in the pipe.
great. I've applied most of your patch and have released the -51-37 kernel. A couple of generic bits i did not apply.
> In the process of producing the patch I stumbled across a change > introduced in 51-15 where in the case of PREEMPT_RT it appears > hw_irq_controller.end() is never being called at the end of > do_hardirq(). This appears to be an oversight in the code and the > existing PPC openpic code does register a end() handler which it > expects to be called in order to terminate the interrupt. Otherwise > interrupts at the current level are effectively disabled.
this change was fully intentional. Basically on PREEMPT_HARDIRQS, the 'redirected' interrupt path is special already. Right now when an IRQ is redirected, we do the following: ->ack() in the hardirq handler and no ->end() (so we keep the interrupt masked), then the handling of the IRQ sometime later in its interrupt thread, and an ->enable(). It's a bit unclean, but this results in minimal per-arch changes to the IRQ code. Nevertheless i have applied your change, but we need to get rid of this.
> There is also what I suspect to be some "leaking" of the > __RAW_LOCAL_ILLEGAL_MASK bit out of the local_irq*() API primitives as > the *flags argument. This may subsequently be used by non-local_irq*() > primitives and wind up unintentionally setting the > __RAW_LOCAL_ILLEGAL_MASK bit in the machine control register with > unpredictable results.
i have not applied the generic bits for this, because it should be solved within the raw_local_irq*() code: check for the illegal bit if IRQ debugging is turned on. We very much want to know about mismatched IRQ flags.
> Lastly there is a problem I've yet to isolate in > kernel/printk.c:release_console_sem() where the expansion of > spin_unlock_irq(&logbuf_lock) generating a call to > __raw_local_irq_enable() will lockup console output on PPC. In the > interim this has been reverted to a spin_unlock() call for the case of > PREEMPT_RT && PPC.
i have not applied this one either, please investigate it further, it ought to work.
Also, i have not applied the timer.c change yet either: what kind of bug are you trying to fix there?
Ingo - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |