On 2016-06-30 12:49, Gabriele Sonnu wrote:
> Hi,
> 
> I'm trying to run a custom minimal RT OS inside Jailhouse.
> I successfully booted it by making a custom loader, but it freezes
> trying to use the timer - it just waits forever for the interrupt to be
> served.
> The OS is single core, and uses the legacy method (non APIC) to program
> interrupts.
> 
> Is there a way to tell Jailhouse to serve legacy interrupt?

Legacy interrupts, yes, but only via APIC/IOAPIC, and only if they are
not shared with other devices that do not belong to that cell. We do not
want to fiddle with PIC/PIT any more, that would just grow the
hypervisor complexity.

If we have an RTOS that does not support APIC/IOAPIC yet, you either
need to adjust it or switch to RT-KVM (KVM on PREEMPT-RT) as a
hypervisor. It can do PIT/PIC emulation in the kernel and with certain
RT qualities, though I never tested that in details (only had
APIC/IOAPIC guests so far).

Jan

-- 
Siemens AG, Corporate Technology, CT RDA ITP SES-DE
Corporate Competence Center Embedded Linux

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