On Sun, Jun 5, 2011 at 08:27, Brad Boyer <flar@xxxxxxxxxxxxx> wrote:
If we could really map all the interrupt controllers, we could probably
cut down on the largest interrupt number. Most Macs really only have
20 or 30 actual interrupt sources. The problem is the two or three
layers of cascaded mess. None of them have just a single layer. Just
getting rid of the fixed global mapping could take us down to 64 since
nothing has both Baboon and PSC, but we have unique numbers for them.
We have 3 whole blocks of 8 just for PSC, even though that's just in
two models. We don't even know what most of those do, if anything.
While looking into optimizing interrupts using chain handlers (which cannot
be shared), I noticed several of these cascades are hung on the same interrupt.
Hence we cannot use the optimization of chain handlers for them.
Knowing which are mutually exclusive helps a lot, but my Mac knowledge is
very limited.
I derived from the code this list of cascade handlers and the
interrupts they use:
baboon_irq
IRQ_NUBUS_C
oss_irq
OSS_IRQLEV_SCSI = IRQ_AUTO_2 conflict: via2_irq
OSS_IRQLEV_SOUND = IRQ_AUTO_5 conflict: psc_irq
oss_nubus_irq
OSS_IRQLEV_NUBUS = IRQ_AUTO_3 conflict: psc_irq
psc_irq
IRQ_AUTO_3 conflict: oss_nubus_irq
IRQ_AUTO_4
IRQ_AUTO_5 conflict: oss_irq
IRQ_AUTO_6 conflict: via1_irq
via1_irq
OSS_IRQLEV_VIA1 = IRQ_AUTO_6 (on oss) conflict: psc_irq
IRQ_AUTO_1 conflict: iop_ism_irq
IRQ_AUTO_6 (if via_alt_mapping) conflict: psc_irq
via2_irq
IRQ_AUTO_2 conflict: oss_irq
via_nubus_irq
IRQ_MAC_NUBUS = IRQ_VIA2_1
These are other interrupts using in the Mac core code, which may use the same
interrupts as some of the cascades above:
iop_ism_irq
OSS_IRQLEV_IOPISM = 1 = IRQ_AUTO_1 (on oss) conflict: via1_irq
IRQ_VIA2_0 (on !oss)
mac_nmi_handler
IRQ_AUTO_7
timer handler
IRQ_MAC_TIMER_1 = IRQ_VIA1_6
So baboon and PSC are mutually exclusive? But they don't conflict w.r.t. to
interrupt lines anyway, so they're not an issue.
From the code, OSS and VIA are also mutually exclusive (except for via1_irq)?
But PSC can coexist with OSS? That's where most of the conflicts are.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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