I too cannot boot the linux-image-5.4.0-52-lowlatency kernel , here's the last couple of lines before a hang
- Unstable clock detected, switching default tracing clock to "global" - If you want to keep using the local clock, then add : "trace_clock=local" - on the kernel command line - random: fast init done - random: crng init done After reverting back to linux-image-5.4.0-51-lowlatency kernel, here are the lines around those "random" lines dmesg | grep -C 1 random [ 0.556570] Memory: 32820996K/33548288K available (14339K kernel code, 2402K rwdata, 4964K rodata, 2648K init, 5056K bss, 727292K reserved, 0K cma-reserved) [ 0.556583] random: get_random_u64 called from kmem_cache_open+0x2d/0x410 with crng_init=0 [ 0.556826] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=8, Nodes=1 -- [ 1.543599] scsi 0:0:0:0: CD-ROM PIONEER DVD-RW DVR-109 1.17 PQ: 0 ANSI: 5 [ 1.588068] random: fast init done [ 1.602701] sr 0:0:0:0: [sr0] scsi3-mmc drive: 40x/40x writer cd/rw xa/form2 cdda tray -- [ 1.644831] Run /init as init process [ 1.665648] random: systemd-udevd: uninitialized urandom read (16 bytes read) [ 1.666883] random: systemd-udevd: uninitialized urandom read (16 bytes read) [ 1.666953] random: systemd-udevd: uninitialized urandom read (16 bytes read) [ 1.693102] usb 1-1: new full-speed USB device number 2 using uhci_hcd -- [ 4.010375] sd 2:0:0:0: [sdb] Attached SCSI disk [ 5.084547] random: crng init done [ 5.084609] random: 7 urandom warning(s) missed due to ratelimiting [ 6.083105] ata4: SATA link down (SStatus 0 SControl 0) --------------------- I'm thinking this is an issue with random number generation This is an older machine with no TPM chip or random number generation support in the CPU, here's the first cpu's info cat /proc/cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 23 model name : Intel(R) Xeon(R) CPU E5420 @ 2.50GHz stepping : 10 microcode : 0xa0b cpu MHz : 1994.962 cache size : 6144 KB physical id : 0 siblings : 4 core id : 0 cpu cores : 4 apicid : 0 initial apicid : 0 fpu : yes fpu_exception : yes cpuid level : 13 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ht tm pbe syscall nx lm constant_tsc arch_perfmon pebs bts rep_good nopl cpuid aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm dca sse4_1 xsave lahf_lm pti tpr_shadow vnmi flexpriority dtherm bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit bogomips : 4987.45 clflush size : 64 cache_alignment : 64 address sizes : 38 bits physical, 48 bits virtual power management: -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1900728 Title: Ubuntu boot failure after upgrade to kernel 5.4.0-52 Status in linux package in Ubuntu: Confirmed Bug description: I'm on Ubuntu 20.04 LTS. After upgrading from linux 5.4.0-51 to 5.4.0-52 today, the computer boots into initramfs (Busybox) every time I reboot. No disk errors found there. If I use the grub menu to switch back to 5.4.0-51, the system boots and runs normally. This is on a Lenovo P53s laptop running Ubuntu only (no dual boot). ProblemType: Bug DistroRelease: Ubuntu 20.04 Package: linux-image-5.4.0-51-generic 5.4.0-51.56 ProcVersionSignature: Ubuntu 5.4.0-51.56-generic 5.4.65 Uname: Linux 5.4.0-51-generic x86_64 ApportVersion: 2.20.11-0ubuntu27.6 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: scott 1624 F.... pulseaudio CasperMD5CheckResult: skip CurrentDesktop: ubuntu:GNOME Date: Tue Oct 20 09:03:33 2020 InstallationDate: Installed on 2020-06-26 (115 days ago) InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423) MachineType: LENOVO 20N6S00B00 ProcEnviron: TERM=xterm-256color PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=en_US.UTF-8 SHELL=/bin/bash ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-5.4.0-51-generic root=/dev/mapper/vgubuntu-root ro quiet splash RelatedPackageVersions: linux-restricted-modules-5.4.0-51-generic N/A linux-backports-modules-5.4.0-51-generic N/A linux-firmware 1.187 SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 08/12/2020 dmi.bios.vendor: LENOVO dmi.bios.version: N2IET91W (1.69 ) dmi.board.asset.tag: Not Available dmi.board.name: 20N6S00B00 dmi.board.vendor: LENOVO dmi.board.version: SDK0J40697 WIN dmi.chassis.asset.tag: No Asset Information dmi.chassis.type: 10 dmi.chassis.vendor: LENOVO dmi.chassis.version: None dmi.modalias: dmi:bvnLENOVO:bvrN2IET91W(1.69):bd08/12/2020:svnLENOVO:pn20N6S00B00:pvrThinkPadP53s:rvnLENOVO:rn20N6S00B00:rvrSDK0J40697WIN:cvnLENOVO:ct10:cvrNone: dmi.product.family: ThinkPad P53s dmi.product.name: 20N6S00B00 dmi.product.sku: LENOVO_MT_20N6_BU_Think_FM_ThinkPad P53s dmi.product.version: ThinkPad P53s dmi.sys.vendor: LENOVO To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1900728/+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