[Bug 1911959] Re: Fresh Ubuntu 20.04 won't boot after intel-microcode update on ThinkPad T460s

[Alban VACHETTE]

I have the same issue on my asus UX303UB.

I downgraded intel-microcode to version "3.20191115.1ubuntu3" in order
to boot my PC.

Here is the output of the command "lscpu" on my PC :

Architecture:                    x86_64
CPU op-mode(s):                  32-bit, 64-bit
Byte Order:                      Little Endian
Address sizes:                   39 bits physical, 48 bits virtual
CPU(s):                          4
On-line CPU(s) list:             0-3
Thread(s) per core:              2
Core(s) per socket:              2
Socket(s):                       1
NUMA node(s):                    1
Vendor ID:                       GenuineIntel
CPU family:                      6
Model:                           78
Model name:                      Intel(R) Core(TM) i5-6200U CPU @ 2.30GHz
Stepping:                        3
CPU MHz:                         2700.033
CPU max MHz:                     2800,0000
CPU min MHz:                     400,0000
BogoMIPS:                        4800.00
Virtualization:                  VT-x
L1d cache:                       64 KiB
L1i cache:                       64 KiB
L2 cache:                        512 KiB
L3 cache:                        3 MiB
NUMA node0 CPU(s):               0-3
Vulnerability Itlb multihit:     KVM: Mitigation: VMX disabled
Vulnerability L1tf:              Mitigation; PTE Inversion; VMX conditional cache flushes, SMT vulnerable
Vulnerability Mds:               Mitigation; Clear CPU buffers; SMT vulnerable
Vulnerability Meltdown:          Mitigation; PTI
Vulnerability Spec store bypass: Mitigation; Speculative Store Bypass disabled via prctl and seccomp
Vulnerability Spectre v1:        Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2:        Mitigation; Full generic retpoline, IBPB conditional, IBRS_FW, STIBP conditional, RSB filling
Vulnerability Srbds:             Vulnerable: No microcode
Vulnerability Tsx async abort:   Not affected
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 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon
                                  pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic movbe popcn
                                 t tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb invpcid_single pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid ept_ad fsgs
                                 base tsc_adjust bmi1 avx2 smep bmi2 erms invpcid mpx rdseed adx smap clflushopt intel_pt xsaveopt xsavec xgetbv1 xsaves dtherm ida arat pln pts hwp hwp_notify hwp_act_window hwp_
                                 epp md_clear flush_l1d

** Changed in: intel-microcode (Ubuntu)
       Status: New => Confirmed

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https://bugs.launchpad.net/bugs/1911959

Title:
  Fresh Ubuntu 20.04 won't boot after intel-microcode update on ThinkPad
  T460s

Status in intel-microcode package in Ubuntu:
  Confirmed

Bug description:
  Installed Ubuntu 20.04 from USB disk using the first Ubuntu 20.04
  installation image released end of April. The system installs and
  boots fine. Then, I run a system update via `apt update && apt
  upgrade` with updates to Ubuntu 20.04.1. intel-microcode is updated on
  this occasion to version 3.20201110.0ubuntu0.20.04.2. Update
  installation succeeds but subsequent reboots most of the time fail. I
  can access GRUB but a normal boot of any of the installed kernels
  results in either a black screen or a screen with a cursor blinking ad
  infinitum. Booting in recovery mode via GRUB and then "resume" works,
  but external display is not detected in this case. Sometimes however
  (maybe 1/5 of the time), making a reboot from this state works.

  When I uninstall intel-microcode via `apt purge intel-microcode` the
  problems disappear. I can boot the system without any problem.

  I had occasional boot problems already since several months, but they
  could be resolved by just rebooting (pressing the power key for a long
  time). After the latest update, this wouldn't work anymore, so in the
  end I tried out re-installing Ubuntu which resulted in the problems
  described above.

  I'm using a Lenovo ThinkPad T460s with system firmware version
  N1CET37W (1.05) which is quite old.

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