Strange kernel error after upgrade

adesh · 2017-08-05 15:25:39

I updated my system after a long time and now I'm seeing this weired error during boot.

[    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.12.4-1-ARCH #1
[    0.000000] Hardware name: Hewlett-Packard Compaq Presario CQ40 Notebook PC/3607, BIOS F.66 05/18/2010
[    0.000000] task: db747280 task.stack: db740000
[    0.000000] EIP: warn_invalid_dmar.part.14+0x55/0x70
[    0.000000] EFLAGS: 00210002 CPU: 0
[    0.000000] EAX: 00000066 EBX: db6b225a ECX: db8b0f88 EDX: 00000000
[    0.000000] ESI: 00000000 EDI: 00000000 EBP: db741ee0 ESP: db741eb0
[    0.000000]  DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
[    0.000000] CR0: 80050033 CR2: 00000000 CR3: 1b89f000 CR4: 00000690
[    0.000000] Call Trace:
[    0.000000]  dmar_validate_one_drhd+0x106/0x140
[    0.000000]  ? acpi_os_signal_semaphore+0x5/0x50
[    0.000000]  dmar_walk_remapping_entries+0x8b/0x1c0
[    0.000000]  detect_intel_iommu+0x58/0xd7
[    0.000000]  ? clkdev_alloc+0x30/0x30
[    0.000000]  pci_iommu_alloc+0x45/0x5f
[    0.000000]  mem_init+0x1c/0x1cc
[    0.000000]  start_kernel+0x1d3/0x3bc
[    0.000000]  i386_start_kernel+0x94/0x98
[    0.000000]  startup_32_smp+0x16b/0x16d
[    0.000000] Code: 00 00 00 e8 2e 4f 07 00 89 45 f0 b8 01 00 00 00 e8 21 4f 07 00 8b 4d ec 8b 55 f0 51 52 50 53 57 56 68 e8 4f 6e db e8 50 4d d7 ff <0f> ff 83 c4 1c 8d 65 f4 5b 5e 5f 5d c3 8d b4 26 00 00 00 00 8d

Some relevant outputs:

[20:32]$ lscpu 
Architecture:        i686
CPU op-mode(s):      32-bit, 64-bit
Byte Order:          Little Endian
CPU(s):              1
On-line CPU(s) list: 0
Thread(s) per core:  1
Core(s) per socket:  1
Socket(s):           1
Vendor ID:           GenuineIntel
CPU family:          6
Model:               15
Model name:          Genuine Intel(R) CPU             575  @ 2.00GHz
Stepping:            13
CPU MHz:             1995.052
BogoMIPS:            3991.35
L1d cache:           32K
L1i cache:           32K
L2 cache:            1024K
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 tm pbe nx lm constant_tsc arch_perfmon pebs bts cpuid aperfmperf pni dtes64 monitor ds_cpl tm2 ssse3 cx16 xtpr pdcm lahf_lm dtherm
[20:32]$ uname -a
Linux addy-pc 4.12.4-1-ARCH #1 SMP PREEMPT Fri Jul 28 19:30:37 UTC 2017 i686 GNU/Linux
[20:32]$

Full dmesg log.
I have intel-ucode installed and configured.

Despite the above error system is perfectly usable and shows no other signs of issues. I would like to understand what this error is and how it can be prevented.

alphaniner · 2017-08-08 17:31:23

Something very similar here which indicates it's due to a BIOS bug and nothing to worry about.

You could look for an updated BIOS, but even if one exists there's no guarantee it will contain a fix.

adesh · 2017-08-09 07:30:56

Thanks alphaniner for your response! Good to know that this warning can safely be ignored.
BTW, this laptop is pretty old and BIOS is up-to-date (May 2010) as per the manufacturer.

Just being curious, I searched a little about this DMAR and IOMMU and it seems to have some relation to virtualization. Now, given that I've never thought about virtualization in my head, it intrigues me - why is my system being probed for virtualization capabilities?

alphaniner · 2017-08-09 17:41:46

Even though I first heard about IOMMU in relation to device passthrough for virtualization, I think it's much more fundamental than that. You can find references to it from the early nils. Not sure about DMAR though.

Arch Linux

#1 2017-08-05 15:25:39

Strange kernel error after upgrade

#2 2017-08-08 17:31:23

Re: Strange kernel error after upgrade

#3 2017-08-09 07:30:56

Re: Strange kernel error after upgrade

#4 2017-08-09 17:41:46

Re: Strange kernel error after upgrade

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