Messages in this thread | | | Date | Wed, 1 Jun 2005 17:44:07 -0600 (MDT) | From | Zwane Mwaikambo <> | Subject | Re: RT patch acceptance |
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On Wed, 1 Jun 2005, Nicolas Pitre wrote:
> On Wed, 1 Jun 2005, Andrea Arcangeli wrote: > > > On Wed, Jun 01, 2005 at 05:29:48PM -0400, Nicolas Pitre wrote: > > > Actualy it's RTAI/rtlinux which is broken wrt the above IRQ disable. > > > See for yourself when they're used and watch RTAI/rtlinux crash. > > > > Well it's not so clear so please elaborate since I'm curious. Especially > > it'd be interesting to know if this is that an arm specific kernel > > crash, or would it happen on x86 too? > > It would happen on any architecture supporting XIP from flash. > > The XIP code therefore polls the IRQ controller (with IRQs masked out) > and whenever an IRQ is pending the flash operation is suspended and IRQs > unmasked. In this case the hard IRQ latency is function of the flash > suspend delay which is documented in the datasheet. > > > There sure can be arch dependencies where an hard_local_irq_disable can > > be necessary in some places, but that's quite a separate topic, and on > > x86 I don't see why it should crash. > > It would crash if the kernel is XIP. If not XIP then the > local_irq_save() is never encountered in that case.
Hmm that's an interesting case, there are a few others, like MMU,TLB update paths and IRQ controller register accesses. But overall these are few and easy to identify.
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