Re: Immediate "system reset" when booting UEFI?
On Fri, Nov 01, 2024 at 09:54:14AM -0400, Lars Kellogg-Stedman wrote:
Hey folks,
I'm running libvirt 10.1.0/qemu-system-x86-core-9.0.1-1.fc40.x86_64 on Fedora
40. I'm trying to boot an Ubuntu image in UEFI mode, like this:
virt-install -r 2048 -n ubuntu.virt --os-variant ubuntu24.04 \
--disk
pool=default,size=10,backing_store=mantic-server-cloudimg-amd64.img,backing_format=qcow2
\
--cloud-init root-ssh-key=$HOME/.ssh/id_ed25519.pub \
--boot uefi
This results in the domain booting up and then immediately resetting:
BdsDxe: loading Boot0001 "UEFI Misc Device" from
PciRoot(0x0)/Pci(0x2,0x3)/Pci(0x0,0x0)
BdsDxe: starting Boot0001 "UEFI Misc Device" from
PciRoot(0x0)/Pci(0x2,0x3)/Pci(0x0,0x0)
Reset System
Domain creation completed.
At this point, the machine is actually powered down and needs to be
restarted manually:
virsh start ubuntu.virt
This works fine, and the domain boots successfully, but now the cloud-init
metadata provided by the `--cloud-init` option to `virt-install` is no longer
available (because this is no longer the initial, virt-install managed boot of
the domain).
What is causing the firmware to reset the system when it first boots?
This will be shim configuring the NVRAM bootloade entries.
You've taken a pre-installed disk image, but have not been provided
the associated UEFI NVRAM that was populated when the disk was first
installed. This is normal, since the NVRAM created at the time is
not guaranteed to be compatible with your EFI binary.
Your VM is booting with a clean NVRAM, and no bootloader entries will
be present. Thus EFI launches the default binary $ESP/EFI/BOOT/BOOTX64.EFI,
which is a copy of shim.
Shim sees that has been launched with no bootloader entries present,
and so will then invoke $ESP/EFI/BOOT/fbx64.efi which will read the
info in $ESP/<vendor>/BOOTX64.CSV file and create boot loader entries
in the EFI NVRAM. Then it will trigger a system reset, which is the
one you see. <vendor> in your case is probably 'ubuntu' I guess.
When you run virsh start, EFI will see bootloader entries and so
instead of $ESP/EFI/BOOT/BOOTX64.EFI, it will probably be launching
$ESP/EFI/ubuntu/shim.efi, which will then run grub, etc, as normal
The latter will be done forever more, unless you purge the NVRAM
of all bootloader entries.
Ideally virt-install would be aware of this and automatically restart
the VM after shim populates the NVRAM. Depends if we can come up with
a relativel foolproof way to identify this situation.
With regards,
Daniel
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