benjojo.co.uk

benjojo posted 19 Jan 2025 17:05 +0000

Fascinating. I accidentally collided the chassis door with the motherboard on this machine I am working on, and dmesg complained about a unsolicited IRQ!

[  149.409381] irq 16: nobody cared (try booting with the "irqpoll" option)

I wonder what actually happened here on the electrical level!

manawyrm@chaos.socia.. replied 19 Jan 2025 17:08 +0000
in reply to: https://benjojo.co.uk/u/benjojo/h/Gg5SgBLQtW3BPR5l1q

@benjojo chassis intrusion switch with missing acpi entry for that interrupt?

benjojo replied 19 Jan 2025 17:22 +0000
in reply to: https://chaos.social/users/manawyrm/statuses/113856120181330379

@manawyrm na this is a consumer mobo+case, so there is nothing like that to be set off!

manawyrm@chaos.socia.. replied 19 Jan 2025 17:23 +0000
in reply to: https://benjojo.co.uk/u/benjojo/h/3ms1xj7nX63rk4Dg6c

@benjojo fun!

nblr@chaos.social replied 19 Jan 2025 17:09 +0000
in reply to: https://benjojo.co.uk/u/benjojo/h/Gg5SgBLQtW3BPR5l1q

@benjojo You know what to do.

benjojo replied 19 Jan 2025 17:23 +0000
in reply to: https://chaos.social/users/nblr/statuses/113856124282541629

@nblr Sadly this is my "misc" machine (LTO tape, SSD wipe, Weird PCIe test bench, etc) that I would quite prefer to stay alive :)

jimthewhyguy@techfie.. replied 19 Jan 2025 17:13 +0000
in reply to: https://benjojo.co.uk/u/benjojo/h/Gg5SgBLQtW3BPR5l1q

@benjojo Wait, that's the ACTUAL message - "nobody cared"? 🤣

benjojo replied 19 Jan 2025 17:24 +0000
in reply to: https://techfieldday.net/users/jimthewhyguy/statuses/113856139094169764

@jimthewhyguy oh the kernel is full of these things, maybe the best one is: "Dazed and confused, but trying to continue": https://github.com/torvalds/linux/blob/fda5e3f284002ea55dac1c98c1498d6dd684046e/arch/x86/kernel/nmi.c#L240

dickenhobelix@chaos... replied 19 Jan 2025 17:08 +0000
in reply to: https://benjojo.co.uk/u/benjojo/h/Gg5SgBLQtW3BPR5l1q

@benjojo Just a wild guess: some capacitors are built from dielectrics with piezoelectric properties. Thus by mechanically stressing the mainboard and the components soldered onto it, you may have built up enough charge in one of those caps to actually cause an interrupt.