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

[Juergen Gross <jgross@xxxxxxxx>]

On 30.07.24 06:02, A Kundu wrote:
> 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.
The mentioned documentation hasn't seen any updates since 2008 in the
part you are interested in. I believe the most sane action would be to
remove the "Kexec" chapter completely.

With Xen I'm not aware of any use case nowadays other than that explained
in the "Kdump" chapter.


Juergen

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