Error: Unable to handle kernel paging request at virtual address

[Bob_NXP_user]

Hello everybody,

I'm tryng to debug my Linux OS for a custom iMX93 board. I'm able to start the OS but sometimes I get the following error while booting:
  

the weird fact is that this happens randomly! Sometimes I don't have problems at all, other times it hangs with this error and in different "locations" of the log! I understand that this error means that it cannot initialize a driver, comparing the error log with the correct one I'm able to discover which driver is not working. I'm wondering if could be a problem linked to the RAM settings. In particular when the OS starts, I notice that the RAM memory is not correctly recognized by the kernel (2 GB while I have only 256 MB):
 

Can anyone help me to understand what's going on?

Regards, 

Bob

[Bio_TICFSL]

Hello,

The "Unable to handle kernel paging request at virtual address" error, often accompanied by a kernel panic, typically indicates a problem with memory access or mapping during kernel operations. This error can be caused by issues with device drivers, incorrect RAM settings, or even kernel bugs. 

Possible Causes and Solutions:

• Incorrect RAM Settings: The kernel might not be correctly recognizing or mapping the physical RAM.  Device Driver Issues: A faulty or incompatible device driver could be trying to access memory incorrectly, triggering the error. 

• Kernel Bugs: In some cases, the error might be due to a bug in the kernel itself, especially if the error occurs randomly or consistently at different virtual addresses. 
• DMA Problems: DMA (Direct Memory Access) issues can also lead to paging errors, particularly if the DMA engine attempts to access a memory region that's not properly mapped. 
• Memory Corruption: If there's memory corruption within the kernel, it can cause issues with paging. 

Troubleshooting Steps:

1. 1. Identify the Specific Virtual Address:

   The error message will include a virtual address where the problem is occurring. This address can help pinpoint the potentially problematic driver or memory region. 

• 2. Check Driver Compatibility:

  If you recently installed or updated a driver, try rolling back to a previous version to see if that resolves the issue. 
• 3. Verify RAM Settings:

  Ensure the RAM is correctly recognized by the kernel, and try different RAM settings if possible. 
• 4. Enable Kernel Debugging:

  If possible, enable kernel debugging options to gather more information about the error, particularly related to MMU and VMA structures. 
• 5. Check for Kernel Bugs:

  If the error is reproducible, it could be a kernel bug. Consult the kernel's documentation or relevant forums for known issues. 
• 6. Examine DMA Usage:

  If your system uses DMA, investigate how memory is allocated and mapped for DMA operations. Incorrect memory allocation can lead to paging errors. 
• 7. Consider Stack Overflow:

  If the error occurs during a specific kernel function, check for potential stack overflow issues. 
• 8. Monitor Memory Usage:

  If the system runs out of memory, it can also cause paging errors. Ensure you have sufficient memory available. 
  Regards

[Bob_NXP_user]

Hello,

Regarding the troubleshooting steps:

1. the virtual address changes! Everytime I reboot the board, and the problem occurs, the virtual address is never the same (when it doesn't work, because sometimes the kernel works!).

2. I didn't update any driver, I used the kernel version provided by NXP 6.12.y. I'm currently disabling all the drivers that I don't need in the menuconfig.

3. I set a bootarg ( mem=256M) in U-boot environment to let the kernel recognize the RAM size, otherwise it set 2GB by default. I don't know if it is the right way, please tell me.

5. The error changes.

6. Please, can you tell me how it has to be?

7,8 need to be examined.

Thanks in advance.

Regards,

Bob

[Bio_TICFSL]

Hello,

A1. Erase yocto and restart building again.

A2, try to check the CMEM variable in uboot.

Regards

[Bob_NXP_user]

Hello  @Bio_TICFSL ,

Already done various builds, I still get the same random problem. Furthermore I didn't find the cmem variable.

Do you have any other suggestion regarding the possible cause of this weird behavior?

Regards,

Bob