Re: [Qemu-devel] [PATCH 8/9] isa: refine irq reservations

[Blue Swirl]

On Mon, Sep 14, 2009 at 6:49 PM, Gerd Hoffmann <address@hidden> wrote:
> There are a few cases where IRQ sharing on the ISA bus is used and
> possible.  In general only devices of the same kind can do that.
> A few use cases:
>
>  * serial lines 1+3 share irq 4
>  * serial lines 2+4 share irq 3
>  * parallel ports share irq 7
>  * ppc/prep: ide ports share irq 13

There is another ppc/prep case where RTC and m48t59 share irq 8. The
attached patch converts m48t59 to ISA and makes this more visible.

Does sharing of IRQs really have to be fatal? Wasn't ISA bus edge
triggered and so IRQ sharing was a bit unreliable (but not completely
broken) also on real HW?

0001-PPC-use-ISA-version-of-m48t59-for-PREP-machine.patch
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