[SRU Justification] [Impact]
Current linux-azure-4.15 kernel in bionic fails to boot Standard_M416s_v2 VM because of x2apic being disabled: [ 0.000000] x2apic: IRQ remapping doesn't support X2APIC mode [ 0.000000] unchecked MSR access error: WRMSR to 0x1b (tried to write 0x00000000fee00100) at rIP: 0xffffffff9325d1f8 (native_write_msr+0x8/0x30) [ 0.000000] Call Trace: [ 0.000000] __x2apic_disable.part.5+0x49/0x80 [ 0.000000] enable_IR_x2apic+0x123/0x18c [ 0.000000] default_setup_apic_routing+0x16/0x73 [ 0.000000] apic_intr_mode_init+0x84/0x91 [ 0.000000] x86_late_time_init+0x24/0x2b [ 0.000000] start_kernel+0x444/0x505 [ 0.000000] x86_64_start_reservations+0x24/0x26 [ 0.000000] x86_64_start_kernel+0x74/0x77 [ 0.000000] secondary_startup_64+0xa5/0xb0 [ 0.000000] x2apic disabled [ 0.000000] Switched APIC routing to physical flat. [Test Plan] Run updated kernel (with x2apic support backported from linux-azure-5.4 kernel). It should boot fine and display: [ 0.000000] Setting APIC routing to physical x2apic. [Where problems could occur] Potentially x2apic may now be used on other VM instances. [Other Info] None. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux-azure in Ubuntu. https://bugs.launchpad.net/bugs/1951924 Title: linux-azure 4.15 fails to boot on Standard_M416s_v2 in Azure Status in linux-azure package in Ubuntu: Confirmed Bug description: To reproduce: * start a bionic VM in azure: az vm create --name bionic --resource-group test-bionic --image "Canonical:UbuntuServer:18_04-lts-gen2:latest" --size Standard_M416s_v2 --admin-username ubuntu --ssh-key-value SSH_KEY_PATH * "downgrade" the kernel to 4.15 and delete the 5.4 kernel * reboot (the machine should fail to boot) The serial console logs can be found on the azure portal (boot diagnostic needs to be enabled for the VM first). Logs: https://pastebin.ubuntu.com/p/mhKMdMJCtX/ To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-azure/+bug/1951924/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
