Public bug reported: A Gen-1 Ubuntu 19.10 VM on Azure was created and upgraded to Ubuntu 20.04 by “do-release-upgrade –d”.
Then the latest Ubuntu v5.6 kernel was installed from https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.6/. As soon as a reboot was performed, a panic with the v5.6 kernel occured because the rootfs can not be found. It turns out by default, initramfs does not get loaded: /boot/grub/grub.cfg: menuentry 'Ubuntu' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-3d2737e8- b95a-42bf-bac1-bb6fb4cda87f' { … if [ "${initrdfail}" = 1 ]; then linux /boot/vmlinuz-5.6.0-050600-generic root=PARTUUID=bc3d472f-401e-4774-affa-df1acba65a73 ro console=tty1 console=ttyS0 earlyprintk=ttyS0 ignore_loglevel sysrq_always_enabled unknown_nmi_panic initrd /boot/initrd.img-5.6.0-050600-generic else linux /boot/vmlinuz-5.6.0-050600-generic root=PARTUUID=bc3d472f-401e-4774-affa-df1acba65a73 ro console=tty1 console=ttyS0 earlyprintk=ttyS0 ignore_loglevel sysrq_always_enabled unknown_nmi_panic panic=-1 #Dexuan: here the initrd line is missing! fi initrdfail } As we can see, Ubuntu only uses the initrd.img if initrdfail=1. Normally, initrdfail = 0, so when we boot the v5.6 kernel for the first time, we must hit the “fail to mount rootfs” panic and the kernel will automatically reboot…. Also, the “initrdfail” here marks initrdfail=1, so when the kernel boots for the 2nd time, the kernel should successfully boot up. Next, when the kernel boots for the 3rd time, it panics again since the userspace program resets initrdfail to 0, and next time when the kernel boots, it can boot up successfully -- this “panic/success/panic/success” pattern repeats forever… The linux-azure kernels are not affected since they have the vmbus driver and storage drivers built-in (i.e. “=y”): /boot/config-5.3.0-1013-azure:CONFIG_HYPERV_STORAGE=y /boot/config-5.3.0-1013-azure:CONFIG_HYPERV=y /boot/config-5.4.0-1006-azure:CONFIG_HYPERV_STORAGE=y /boot/config-5.4.0-1006-azure:CONFIG_HYPERV=y /boot/config-5.6.0-050600-generic:CONFIG_HYPERV_STORAGE=m /boot/config-5.6.0-050600-generic:CONFIG_HYPERV=m The v5.6 kernel uses =m rather than =y, so is affected here. It looks the setting may be intentional, but we should not assume a customer kernel must have the necessary vmbus/storage drivers built-in. This issue only happens to the Ubuntu Marketplace image (19.10 and maybe 19.04 as well?) on Azure. We installed a Ubuntu 20.04 VM from the .iso file from http://cdimage.ubuntu.com/daily-live/pending/ and don’t see the strange grub issue. ** Affects: grub2 (Ubuntu) Importance: Undecided Status: New ** Affects: linux-azure (Ubuntu) Importance: Undecided Status: New ** Also affects: grub2 (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1870189 Title: initramfs does not get loaded To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1870189/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
