RE: [PATCH] x86/hyperv: Enable 15-bit APIC ID if the hypervisor supports it

[Dexuan Cui]

> From: Dexuan Cui <decui@xxxxxxxxxxxxx>
> Sent: Monday, November 2, 2020 5:12 PM
> 
> ...

Hi tglx,
Now this patch is in the x86/apic branch, which is great! Thanks for the 
quick action! But the third line of the below paragraph of the commit log
is missing... Sorry I just realized I should have not prefixed that line with the
">255 APIC IDs" -- it looks a line is ignored if it starts with 2 chars of ">>". :-(

> On an old Hyper-V host that doesn't support the Extended Dest ID, nothing
> changes with this commit: Linux VM is still able to bring up the CPUs with
> >255 APIC IDs with the help of hyperv-iommu.c, but IOAPIC interrupts still
> can not go to such CPUs, and the kdump kernel still can not work properly
> on such CPUs.