Re: xen on i7-12700

[Greg Troxel <gdt%lexort.com@localhost>]

Responding jointly to you, Manuel and the offlist reply:

It's an ASRock gamer motherboard, not a server motherboard.  I meant
that I am treating it like a server.   I don't have a serial console and
have not yet figured out if I can plug in a connector.  GENERIC sees
  com0 at isa0 port 0x3f8-0x3ff irq 4: ns16550a, 16-byte FIFO
so probably I have to get a cable.  Will consider that if needed.

> I have one machine running a PVH dom0 and it's doing well. It's a:
> cpu0: "Intel(R) Xeon(R) W-2223 CPU @ 3.60GHz"

> For this to work you may want to disable drm

you mean "userconfig=disable drm*" in boot, just like one often wants to
disable troublesome video when running on bare metal?  I'll assume so,
and if not please explain.


I got a suggestion for high frame rate video.  Sure enough, my phone
claims to do 240 fps, and mplayer can single step forward (but not
back?) with . after SPC to pause.  That was hugely illuminating.

xen was loaded and the the dom0 kernel.  A bunch of ok looking stuff and
the last two ok lines (hand typed):

  (XEN) SMP: Allocating 8 CPUs (0 hotplug CPUs)
  (XEN) IRQ limits: 120 GSI, 1544 MSI/MSI-X
  (XEN) --- [Xen-4.18.0-2023116nb0  x86_64  debug=n  Not tainted ] ---
  (XEN) CPU: 0

and then it goes into a backtrace.  the call stack

  intel_iommu_enable_eim+0/0xe0
  iommu_enable_x2apic
  x2apic_bsp_setup
  __start_xen
  __high_start

I noticed in the cpu/chipset config that virtualization at VT-d were
enabled.

With GENERIC booted I was able to modload nvmm and start up one of my
domU images with qemu, except it was unhappy about wd0 vs xbd0.  This
was ok without and with nvmm.


I found a hint that I don't quite follow, that apic: auto on ASrock
motherboards can make x2apic visible to the cpu but the iommu acts as
xapic (not 2).  But I don't find that.

I did enable SR-IOV in the bios.

Unfortunately no change; the crash looks the same.


I will try a debug xen with apic debugging turned on, and look at the
motherboard manual again.