[KEXEC] Lacking documentation and kexec failure with Xen 4.19-rc4 and 4.20-dev on linux host

[A Kundu <avikalpa@xxxxxxxxx>]

I am experiencing issues using kexec to load Xen 4.19-rc4 and
4.20-dev on a debian host.

The current documentation at
https://xenbits.xenproject.org/docs/4.19-testing/misc/kexec_and_kdump.txt
appears to be missing crucial details on properly using kexec
with the --vmm option for loading Xen.

kexec complains the --vmm option is not present.

System information:
$ uname -a
Linux host 6.9.10-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.9.10-1 
(2024-07-19) x86_64 GNU/Linux
$ kexec --version # compiled from source tarball with ./configure --with-xen
kexec-tools 2.0.29

Steps to reproduce:

1. Set variables:

XEN_HYPERVISOR="/boot/xen.gz"
XEN_CMD="dom0_mem=6G dom0_max_vcpus=6 dom0_vcpus_pin cpufreq=xen"

2. Attempt to load Xen 4.19-rc4:

# kexec -l "$XEN_HYPERVISOR" --command-line="$XEN_CMD"
Could not find a free area of memory of 0x3b6001 bytes...
elf_exec_build_load_relocatable: ELF exec load failed

3. Attempt to load Xen 4.20-dev:

# kexec -l "$XEN_HYPERVISOR" --command-line="$XEN_CMD"
Could not find a free area of memory of 0x3f8001 bytes...
elf_exec_build_load_relocatable: ELF exec load failed

4. Follow the steps in the Xen manual at misc/kexec_and_kdump.txt:

# Set variables

XEN_IMAGE="/boot/xen-4.19-rc.gz"
DOM0_IMAGE="/boot/vmlinuz-6.9.10-amd64"
DOM0_INITRD="/boot/initrd.img-6.9.10-amd64"
DOM0_MEMORY="6G"
DOM0_CPUS="0-5"

# Prepare Xen and dom0 command line arguments

XEN_ARGS="no-real-mode dom0_mem=${DOM0_MEMORY}"
DOM0_ARGS="max_cpus=6 dom0_max_vcpus=6 dom0_vcpus_pin"

# Load Xen and dom0 kernel

kexec -l --append="${XEN_ARGS} -- ${DOM0_ARGS}" --initrd=${DOM0_INITRD} \
  --vmm=${XEN_IMAGE} ${DOM0_IMAGE}

Result:
kexec: unrecognized option '--vmm=/boot/xen-4.19-rc.gz'

I have tried compiling kexec-tools 2.0.29 from source using
./configure --with-xen, as well as using debian's apt version, but
both result in the same "unrecognized option '--vmm'" error.

Please provide guidance on the correct steps to get kexec working
for loading Xen 4.19-rc4 and 4.20-dev. Additionally, I kindly
request that the documentation be updated with these details to
assist other users who may encounter this issue.

If you need any further information to investigate this problem,
please let me know.

Thank you for your attention to this matter.

A Kundu