[LinuxBIOS] HT interrupts
segher at kernel.crashing.org
Thu Feb 15 16:07:05 CET 2007
> Sorry to spam again but I couldn't figure out this on my own.
You again replied to an unrelated message instead of starting
a new thread too, sigh.
> 1. Does LinuxBIOS actually program the HT interrupt definition
> based on the interrupt capability and mobo config, or does Linux do
> this? Or
> is it up to the driver?
LinuxBIOS has to do at least some of the configuration. It
probably does it all, I didn't check. Linux will at runtime
change some settings. Unrelated device drivers do not touch
any of this.
> 2. What's the recommended way of doing HT interrupt that will work
> with both
> APIC and 8259? EOI seems to be APIC only (can be turned off in the
> interrupt request) and I guess I can't rely on EOI to always be there?
I have no idea what your question is. You *have* to do EOI
on level triggered interrupts and you *have* to refrain from
using it on edge triggered interrupts, or things will go
(horribly and/or subtly) wrong.
> 3. EOI in a way acts as flow control. So without EOI is it possible
> that I
> can flood the PIC/APIC with too many interrupt packets?
No, only one interrupt packet is sent from the HT APIC over
the HT bus; and only one packet (the EOI packet) is sent
> I suppose the
> credit based flow control in HT can take care of this...
That doesn't prevent flooding, it just prevents losing
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