Re: [PATCH] Revert "x86/apic/x2apic: Implement IPI shorthands support"

[Baoquan He]

On 01/10/23 at 10:24am, Baoquan He wrote:
> On 01/09/23 at 10:59pm, Thomas Gleixner wrote:
> > On Tue, Dec 20 2022 at 13:34, Baoquan He wrote:
> > > This reverts commit 43931d350f30c6cd8c2f498d54ef7d65750abc92.
> > >
> > > On kvm guest with 4 cpus deployed, when adding 'nr_cpus=2' to normal
> > > kernel's cmdline, and triggering crash to jump to kdump kernel, kdump
> > > kernel will stably hang. Reverting commit 43931d350f30 ("x86/apic/x2apic:
> > > Implement IPI shorthands support") can fix it.
> > 
> > Is there any output on the early console or hangs it silently?
> > 
> > If the latter, can you attach GDB to the guest and figure out where it
> > is stuck?
> 
> No any output on the ealry console. I will try gdb debugging. Thanks.

I rebase to the latest upstream kernel and tested, the stable kdump
kernel hang disappear. Seems I need do another round of bisect to see
on which commit it's made to fix that. Will update if any progress.