Hi Anish On Tue, Aug 09, 2022 at 10:10:03PM +0530, Anish Gupta wrote: > Hello all, > I am new to Azure/Hyper-V environment and trying to boot Xen PV. Dom0 Linux on Xen doesn’t detect hv_vmbus and boot fails. I get the same result even with Xen HYPERV_GUEST config. Here is the console logs with latest Xen 4.15.3 and Linux 5.18: > [...] > [ 0.000000] SMBIOS 2.3 present. > [ 0.000000] DMI: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS 090008 12/07/2018 > [ 0.000000] Hypervisor detected: Xen PV <<< > … This is expected. > [ 197.060965] dracut-initqueue[311]: Warning: Could not boot. > [ 197.067020] dracut-initqueue[311]: Warning: /dev/disk/by-uuid/c8396182-9335-4bf7-a963-f14e85f41f23 does not exist > Starting Setup Virtual Console... > [ OK ] Started Setup Virtual Console. > Starting Dracut Emergency Shell... > Warning: /dev/disk/by-uuid/c8396182-9335-4bf7-a963-f14e85f41f23 does not exist > > Generating "/run/initramfs/rdsosreport.txt" > > > Entering emergency mode. Exit the shell to continue. > Type "journalctl" to view system logs. > You might want to save "/run/initramfs/rdsosreport.txt" to a USB stick or /boot > after mounting them and attach it to a bug report. > > > dracut:/# > > > As an experiment I did force load hv_vmbus but then hit a page fault. I will really appreciate guidance in getting it working. > What did the backtrace show? > Was Xen PV ever supported in any version of Xen + Linux on Azure/Hyper-V? I never got the time to make it work with VMBus based devices. The initial development work was done on a Gen1 VM locally with emulated hard drive and network adapter. Azure Gen2 VMs don't have emulated devices. In hv_acpi_init, you can see that if the hypervisor personality is not Hyper-V then that function returns -ENODEV. I think you will need to find a way to initialize VMBus somehow. Fundamentally, you're trying to achieve mixed-personalities in a single system. I think it is going to require non-trivial investment to make it work properly. Thanks, Wei.
