Randomly on my laptop screen this appears and debian just freezes. Sometimes these vertical lines don’t appear and system freezes anyway. Its just random. How do i identify if this is hardware or software issue? and then how to identify exact piece of hardware or software causing this problem.
Could be hardware (chips desoldering themselves, data cable shorting out when heating up, broken RAM), could be software (driver issue, IOMMU configuration, etc).
I would start with testing the memory chips. If those pass, I’d try a much newer/older kernel to see if that makes the problem disappear. If that doesn’t, maybe try running the OS that came with the laptop and verify that it’s a hardware issue. If it doesn’t happen on another OS, it’s probably some form. Of software issue; in that case you’d need to catch the crash somehow, like by plugging a USB-to-serial converter into a USB port, dumping the kernel output to that, and having a second machine monitor the kernel output while you try to trigger the crash.
If all operating systems have the issue, reseating RAM and perhaps any important cables may also help.