Hi,
I'm trying to kexec from a Linux kernel to a Xen supporting multiboot2.
My GRUB2 config manages to launch Xen without any issues, but I haven't
been able to reproduce a similar setup using the latest kexec binary.
Here's the relevant (working) grub.cfg section:
> echo 'Loading Xen 4.14.5 ...'
> if [ "$grub_platform" = "pc" -o "$grub_platform" = "" ]; then
> xen_rm_opts=
> else
> xen_rm_opts="no-real-mode edd=off"
> fi
> multiboot2 /xen-4.14.5.gz placeholder console=none
dom0_mem=min:1024M dom0_mem=max:4096M ucode=scan smt=off
gnttab_max_frames=2048 gnttab_max_maptrack_frames=4096 ${xen_rm_opts}
> echo 'Loading Linux 5.15.64-1.fc32.qubes.x86_64 ...'
> module2 /vmlinuz-5.15.64-1.fc32.qubes.x86_64 placeholder
root=/dev/mapper/qubes_dom0-root ro
rd.luks.uuid=luks-4272e2eb-2f6f-4532-a801-cfb3029b1080
rd.lvm.lv=qubes_dom0/root rd.lvm.lv=qubes_dom0/swap
plymouth.ignore-serial-consoles rd.driver.pre=btrfs rhgb quiet
> echo 'Loading initial ramdisk ...'
> module2 --nounzip /initramfs-5.15.64-1.fc32.qubes.x86_64.img
And here is my unsuccessful attempt at reproducing this behavior (from a
Linux LiveUSB):
> mkdir /mnt/boot && mount /dev/sda2 /mnt/boot && mount /dev/sda1
/mnt/boot/efi
> kexec \
> -l /mnt/boot/xen-4.14.5.gz \
> -t multiboot2-x86 \
> --command-line="console=vga dom0_mem=min:1024M dom0_mem=max:4096M
ucode=scan smt=off gnttab_max_frames=2048 gnttab_max_maptrack_frames=4096" \
> --module="/mnt/boot/vmlinuz-5.15.64-1.fc32.qubes.x86_64
root=/dev/mapper/qubes_dom0-root ro
rd.luks.uuid=luks-4272e2eb-2f6f-4532-a801-cfb3029b1080
rd.lvm.lv=qubes_dom0/root rd.lvm.lv=qubes_dom0/swap
plymouth.ignore-serial-consoles rd.driver.pre=btrfs rhgb" \
> --module="/mnt/boot/initramfs-5.15.64-1.fc32.qubes.x86_64.img"
> kexec -e
After the kexec -e command, the system systematically reboots instead of
loading Xen, with no information about why.
Some things I tried:
* Removing --nounzip from grub.cfg has no effect and Xen still boots.
* Removing "quiet" from the dom0 Linux's command line. Still no output.
* kexec'ing directly into dom0 Linux kernel. This works, but it is not
what I want.
* Adding "no-real-mode" and "no-real-mode edd=off" to Xen's
command-line. No luck.
* Adding "noreboot" to Xen's command-line. With GRUB2 and a forced
crash (e.g. by omitting the module2 instructions), Xen hangs as
expected. With kexec the system reboots nonetheless, with no
information.
* I also stumbled upon [this
article](https://xenbits.xenproject.org/docs/4.14-testing/misc/kexec_and_kdump.txt)
but the `--vmm` option is IA-64 specific, while I'm on x86_64.
I'm running out of ideas how to fix this, is there something I am
unaware with regard to booting a multiboot2 system? Or Xen in
particular? How to reproduce GRUB2's setup using kexec?
Regards,
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