# MCA: CPU 0 UNCOR GTLB LG error



## erdos (Jul 12, 2020)

Hi all,

I've encountered following error several times during system upgrade,

the screen was filled with errors like:


```
MCA: Vendor "AuthenticAMD", ID 0xfc0, APIC ID 0
MCA: CPU 0 UNCOR GTLB LG error
MCA: Address 0x3200038
MCA: Bank 4, Status 0xa40000000005001b
MCA: Global Cap 0x0000000000000105, Status 0x0000000000000000
```

any idea what does this mean?


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## richardtoohey2 (Jul 12, 2020)

Google has this: https://github.com/opnsense/core/issues/1244

Not saying it is exactly the same, but it seems to indicate an unexpected instruction.

What is the machine you are running on?  What's the CPU?


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## erdos (Jul 13, 2020)

thanks!
I'm running on a homebuilt pc with AMD 64 Cpu.

Looks that this is related to the AMD processor.


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## Terry_Kennedy (Jul 24, 2020)

erdos said:


> any idea what does this mean?


An illegal instruction should not cause a machine check to be logged. I would check to make sure your motherboard BIOS is up-to-date and also try the sysutils/devcpu-data port to see if there is newer microcode for your CPU.

The sysutils/mcelog port decodes this machine check as: 
	
	



```
Hardware event. This is not a software error.
CPU 0 BANK 4 
ADDR 0 
MCG status:
STATUS a40000000005001b MCGSTATUS 0
MCGCAP 105 APICID 0 SOCKETID 0 
(Fields were incomplete)[/code[
```


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