"Page fault while in kernel mode" on APU2 after bios/coreboot upgrade

DaddyGo

@CS said in "Page fault while in kernel mode" on APU2 after bios/coreboot upgrade:

the device has been working smoothly without any crashes for about 6 days after I disabled CPB

This means that your problem is CPB dependent, but I really have not heard of anyone else having this problem in the long run.

CPB is not a required feature, but if it already exists and can be enabled, why not use it.
For us, it caused a significant improvement in ExpVPN connections

These links can also be useful:

https://teklager.se/en/knowledge-base/apu2-vpn-performance/
https://teklager.se/en/knowledge-base/apu2-1-gigabit-throughput-pfsense/
https://teklager.se/en/knowledge-base/

btw:
99% of pcEngines users use CPB, the forum is full of APU board descriptions, I think it's a good thing

fireodo

@DaddyGo said in "Page fault while in kernel mode" on APU2 after bios/coreboot upgrade:

btw:
99% of pcEngines users use CPB, the forum is full of APU board descriptions, I think it's a good thing

I have CPB too, and I have tested with and without, there was no difference in the pfsense behavior (beside speed increase), but I think that the original posters APU has RAM that is on the "limit" and the increasing of speed make that RAM to produce errors.
Thats what I suppose.

Fine Weekend,
fireodo

DaddyGo

@fireodo said in "Page fault while in kernel mode" on APU2 after bios/coreboot upgrade:

but I think that the original posters APU has RAM that is on the "limit" and the increasing of speed make that RAM to produce errors.

This is very possible....exhausted RAM

no matter how good the APU stuff is, 4GB of RAM was often on the "verge" for me

Don't forget @fireodo that 3mdeb (BIOS developers) has been activating RAM ECC for some time

so this should help with RAM errors

fireodo

@DaddyGo said in "Page fault while in kernel mode" on APU2 after bios/coreboot upgrade:

Don't forget @fireodo that 3mdeb (BIOS developers) has been activating RAM ECC for some time

so this should help with RAM errors

I know - but if the Hardware is not OK (the RAM-Chips) then even ECC cannot compensate that!

DaddyGo

@fireodo said in "Page fault while in kernel mode" on APU2 after bios/coreboot upgrade:

Hardware is not OK

That’s really true, and then we’ll see what the OP gets

CS

@DaddyGo, @fireodo , @stephenw10

Hey folks, let me provide an update here:

Memtest was completed without errors but pfSense kept crashing.
I upgraded coreboot to v4.12.0.5 but it kept crashing.
I reinstalled pfSense 2.4.5-RELEASE-p1 and restored my config but it kept crashing, which is something I was not expecting.
I kept the CPU Boost config option in my loader.conf.local and disabled again the option "Core Performance Boost" in Bios. It stopped crashing and CPU Boost is still active:

dev.cpu.0.temperature: 62.7C
dev.cpu.0.cx_method: C1/hlt C2/io
dev.cpu.0.cx_usage_counters: 24303377 0
dev.cpu.0.cx_usage: 100.00% 0.00% last 1981us
dev.cpu.0.cx_lowest: C1
dev.cpu.0.cx_supported: C1/1/0 C2/2/400
dev.cpu.0.freq_levels: 1400/-1 1200/-1 1000/-1
dev.cpu.0.freq: 1400
dev.cpu.0.%parent: acpi0
dev.cpu.0.%pnpinfo: _HID=none _UID=0
dev.cpu.0.%location: handle=\_PR_.P000
dev.cpu.0.%driver: cpu
dev.cpu.0.%desc: ACPI CPU

Core Performance Boost is triggering this for some reason, it was crashing randomly and not when it was under load.
Could anyone share their APU2 loader.config.local file for reference? I'm wondering if I'm missing something obvious, I haven't done any tuning for years because it has been running smoothly with no issues.

stephenw10

The fact it threw an MCA error implies it was hitting some hardware issue and it looked to be in the RAM.

I'm not entirely sire what the Core Performance Boost setting does but I could well believe it pushes the RAM or bus speed up with the CPU. Your RAM appears to be incapable of running stable at that new rate. Or something lsimilar to that.

Steve

kiokoman

are you sure it's ram?

to me it can be overclocked cpu or burned cpu

MCA: Vendor "AuthenticAMD", ID 0x730f01, APIC ID 1
MCA: CPU 1 COR ICACHE L1 IRD error

Machine Check Architecture

CPU 1
COR = Corrected
ICACHE = Instruction Cache
L1 = L1 Cache (On Chip)
IRD = Instruction Fetch
error is self explanatory.

stephenw10

Nope I'm not sure. And your explanation looks better!

Pretty much the only thinh that made me think it might be ram was:

MCA: Bank 1, Status 0x9400000000000151

Which I assume to be a RAM bank but it could be cache or some other terminology.

Steve

CS

@kiokoman thanks, that's a good point. I have seen crashes with CPU ID 0 and CPU ID 1.

Last three dumps:

Fatal trap 12: page fault while in kernel mode
cpuid = 0; apic id = 00
fault virtual address	= 0x1af
fault code		= supervisor read instruction, page not present
instruction pointer	= 0x20:0x1af
stack pointer	        = 0x28:0xfffffe0118ce1890
frame pointer	        = 0x28:0xfffffe0118ce18f0
code segment		= base 0x0, limit 0xfffff, type 0x1b
			= DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags	= resume, IOPL = 0
current process		= 11 (idle: cpu0)
trap number		= 12
panic: page fault
cpuid = 0
KDB: enter: panic

spin lock 0xffffffff83517de8 (smp rendezvous) held by 0xfffff8009ddbf000 (tid 100206) too long
timeout stopping cpus
panic: spin lock held too long
cpuid = 1
KDB: enter: panic

spin lock 0xffffffff83517de8 (smp rendezvous) held by 0xfffff8008b216620 (tid 100197) too long
timeout stopping cpus
panic: spin lock held too long
cpuid = 1
KDB: enter: panic

kiokoman

it can be useful for others with this kind of errors but

it's the MCI status register, not the RAM bank

ECC error (ADDR valid) 0x9426c0010b000813
ECC error overflow (ADDR valid) 0xd426c0010b000813
ECC error (ADDR invalid) 0x9026c0010b000813
ECC error overflow (ADDR invalid) 0xd026c0010b000813
L1 Cache Data Store error (UE) 0xb600200000000145
**L1 Instruction Cache (Instruction Fetch) error (ADDR valid) 0x9400000000000151**
L1 Instruction Cache (Instruction Fetch) error overflow (ADDR valid) 0xd400000000000151
Bus Unit (L2 Cache) error (UE) 0xb600000000020136
L2 Data Cache (Line Fill) error (ADDR valid) 0x9400400000000136
L2 Data Cache (Line Fill) error overflow (ADDR valid) 0xd400400000000136

this is specific for this CPU:

The error-reporting machine check register banks supported in this processor are:
• MC0: Data cache (DC).
• MC1: Instruction cache (IC). <- "MCA bank 1"
• MC2: Bus unit (BU), including L2 cache.
• MC3: Reserved.
• MC4: Northbridge (NB), including the IO link. These MSRs are also accessible from configuration
space. There is only one NB error-reporting bank, independent of the number of cores.
• MC5: Fixed-issue reorder buffer (FR) machine check registers.

kiokoman

@CS
CPU ID 0 and CPU ID 1 it's probably a dual core cpu ?
timeout stopping CPUs, it was unable to speak with the CPU
with spin lock held too long, it's basically telling you: "I can't wait forever here, so I guess I'll stop and panic"
based on what you had before I would check CPU settings like overclock / voltage / frequency, overheat, and dust on the fan if there is one

Does it seem to be a common problem for Apu2 ? https://forum.netgate.com/topic/156830/could-you-help-me-analyze-these-crashdumps?_=1602587866619

CS

@kiokoman APU2 has a single AMD Embedded G series GX-412TC, 4 CPUs: 1 package x 4 cores.
No overclocking and no active cooling in place for these boards.

Reference: https://pcengines.ch/apu2.htm

kiokoman

ah i didn't understand that the problem was solved
so it was Core Performance Boost
it was probably overclocking the cpu

CS

@kiokoman correct, "Core Performance Boost" was causing it and we were trying to find out why considering that other folks have it enabled on APU2 without experiencing any issues.

kiokoman

we have a saying in Italy, literally translated as ‘not all donuts come out with a hole’ meaning ‘not everything turns out as planned’
it's called "silicon lottery", not all cpu are the same, there is ample opportunity for some microscopic part of a CPU, which works fine at a certain speed/voltage combination, to no work if the speed or voltage is increased.

fireodo

@CS said in "Page fault while in kernel mode" on APU2 after bios/coreboot upgrade:

@DaddyGo, @fireodo , @stephenw10

Could anyone share their APU2 loader.config.local file for reference? I'm wondering if I'm missing something obvious, I haven't done any tuning for years because it has been running smoothly with no issues.

Hi, here the content of my loader.config.local:

legal.intel_ipw.license_ack=1
legal.intel_iwi.license_ack=1
debug.acpi.avoid="_SB_.PCI0.GPIO" (necessary for loading apuled.ko)

if you still have "hint.acpi_perf.0.disabled=1" in your loader.conf.local you will see those increased frecv. in sysctl dev.cpu even when you have disabled CPB in BIOS.

Regards,
fireodo

DaddyGo

@CS said in "Page fault while in kernel mode" on APU2 after bios/coreboot upgrade:

other folks have it enabled on APU2 without experiencing any issues.

I confirm this

we have lot of such units at end users, they are "run" with CPB without any problems
we basically configure these "routers / NGFWs" + pfSense with CPB

CPB as I wrote above has been enabled in the Coreboot BIOS, but can only be interpreted on 1 core with a frequency of 1,400 instead of 1,000 this is good for OpenVPN stuff, for example...

@CS I think don't look for the rabbit in the bush...
this is not an issue whic is caused by CPB or pfSense

I think the APU2 MOBO is damaged somewhere, cold soldering or something like that

which causes a malfunction in the BUS or RAM operation due to the elevated clock....???

maybe try a CPU shock test under linux and insulate the APU2 housing to warm up .....Voilà, maybe there will be results

@kiokoman anyway, this is an AMD embedded series CPU can not really be overdriven, designed for low-power devices
either it works or it doesn't, there is no overclocking it only the CPB allows for a small tuning...

CS

@DaddyGo @fireodo I won't continue troubleshooting this honestly, the board works fine for me with CPB disabled and I still get the boosted CPU frequency by having the right settings in my loader.conf.local. I'm not even sure if my performance would get any better! Actually, I'm now wondering, just out of curiosity, if this happens when you have both, the CPU boost settings in loader.conf.local and the BIOS setting enabled.

AKEGEC

@CS , every hardware has a different outcome in Q.C. Even with the same parts, but a different batch.
Rule of thumb, 4 years lifespan (4 is death in Chinese). Nowadays you should be happy if your electronic works for more than 4 years.

I am not sure how handy you are but you could try heating up the cpu (without thermal paste) with the heat gun on a flat surface. Keep around 10 cm distance with circular motion for around 10-15 mins. But be warn, you could burn the cpu.