How to kexec into Qubes from Linux LiveCD

I tried applying the recommendations of this thread to a real hardware with no luck.

The hardware is a tablet with Intel Ultra 7 155H (Meteor lake) / 64Gb ram / UEFI boot only.

The problem: whatever I do to kexec into xen, after ‘kexec -e’ the screen goes black, the fan slows down, connected USB devices power down, and then nothing happens however long I wait. Kexec into debian installation works just fine.

What I’ve tried:

  • booting host kernel with intel_iommu=igfx_off
  • kexecing from stock debian or custom compiled kernel
  • using patched (RSDP) and unpatched kexec-tools
  • using multiboot and multiboot2 (had to patch kexec-tools to make multiboot2 work)
  • using patched (RSDP, with acpi_rsdp option) and unpatched vanilla xen
  • passing RSDP coming from ACPI and ACPI2 in systab
  • using xen binary from qubes, and compiled vanilla xen 4.17.3 and 4.19
  • passing --mem-min and --mem-max to kexec, with mem-max matching what linux kernel UEFI stub uses
  • passing --reuse-video-type to kexec
  • passing ‘no-real mode edd=off reboot=no vga=current’ to xen

I’m refusing to accept a defeat, therefore couple of questions to kexec and xen gurus of this forum:

  1. Have I missed anything possibly helping me successfully kexec to xen?
  2. Since I have no option of having com port on this tablet, can I try debugging over usb c (as described here: What you may need to pay attention to when you are debugging xen / dom0 on USB 3.0 cable), or is it useless for early xen debugging?