Re: [Xen-devel]Question about qemu interrupt deliver.

[Keir Fraser <keir@xxxxxxxxxxxxx>]

On 29/11/06 10:20, "Keir Fraser" <keir@xxxxxxxxxxxxx> wrote:

> There is always
> the option of allowing the mapping to be dynamically specified to Xen in
> future (e.g., hvmloader could make a choice, install the appropriate ACPI
> DSDT and use a new hypercall to dynamically modify PCI->link and PCI->GSI
> information). It's not clear that level of flexibility will be warranted
> though -- 32 non-legacy GSIs should be plenty to avoid sharing even with a
> static barber-pole INTx->GSI mapping.

Actually I can be more precise than this. I *would* have allowed dynamic
INTx->GSI mapping if it were easy to generate the _PRT in the ACPI DSDT.
Then hvmloader could walk the PCI bus, find all INTx lines, and map them all
to unique GSIs. That would be very nice. *But* the _PRT is embedded in the
DSDT and so generating it during boot is (as far as I am aware) basically
impossible. So since the _PRT is static, the mapping in Xen may as well be
static too.

I'd be very interested in knowing if there are any tricks to inject dynamic
info into the DSDT (e.g., could the _PRT be dynamically generated in AML
based on memory values poked by hvmloader?).

 -- Keir


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