On Wed, 2009-01-14 at 14:42 -0800, Eric W. Biederman wrote: > Jon Masters <jcm@xxxxxxxxxx> writes: > > > On Wed, 2009-01-14 at 12:40 +0100, Ingo Molnar wrote: > > > >> it's not just -rt, but it is also needed for the concept of threaded IRQ > >> handlers - which was discussed at the Kernel Summit to be desired for > >> mainline. > > > > Right. I'm poking at Thomas' patches and hope to post something soon on > > that front - I'm acutely aware that this will be impacted aswell but > > because it's vaguely RT related had banded it under that banner. > > Stepping back a moment. The only way I can see this working reliably > is if we disable the boot interrupt. Anything that leaves the boot interrupt > enabled means that when we disable the primary interrupt the boot interrupt > will scream, and thus we must disable it as well. > > Which leads to my problem with the entire development process of this feature. > > People want the feature. > People don't want to pay attention to the limits of the hardware. > Which leads to countless broken patches proposed. Is a patch broken because hardware has limitations? If that were always true then many of the patches we see in the kernel wouldn't be there. > Which leads me to conclude. > - IRQ handling in the RT kernel is hopelessly broken. Nope. It's done in a very similar way to other real time kernels already out there - really there are only so many ways to do this. > - IRQ threads are a bad idea. Why? IRQ threads actually make life so much easier - you have a task context, you can do everything inside that rather than scheduling all kinds of deferred work (that in RT will be done in another task later), and so forth. > None of this works reliably on level triggered ioapic irqs. Level triggered IOAPIC IRQs have quirks, film at 11! Jon. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
