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>Watchdogs exist on MCUs but also on some "proper" computers All modern computers have watchdog. You can check your logs `journalctl -b | grep watchdog` http

>Watchdogs exist on MCUs but also on some "proper" computers All modern computers have watchdog. You can check your logs `journalctl -b | grep watchdog` https://access.redhat.com/articles/7129255 https://access.redhat.com/articles/7129255

LtdJorge 9mo ago
Yes, but those are done in software
- p_l 9mo ago
  There's generally at least one watchdog device available in most PCs delivered in last decade, but it's not always utilized. Essentially at one point an intel southbridge integrated a basic watchdog on all models, and it started to just... be included. So these days you can find a variation on the TCO timer watchdog in most PCs, even if the exact implementation varies so we now have a bunch of drivers for the different variants.
  - VorpalWay 9mo ago
    Linux doesn't see one on my Ryzen 5600X desktop at least. My Intel Skylake Thinkpad does seem to have two though (iTCO as well as INT3F0D, not sure what that is, but if I interpret the files under /sys correctly it belongs to the LPC/eSPI controller PCIe device, while the TCO watchdog is found under the SMBus PCIe device). In both cases they do have software watchdogs (NMI based) which relies on a hardware timer triggering an NMI in the kernel. But that relies on the NMI handler still working, which is not as good as a real HW watchdog.
    - p_l 9mo ago
      Apparently it depends to a little bit on how the motherboard is designed, theoretically SP5100 watchdog which is part of the CPU logic in recent ryzens, apparently, is supposed to be enabled if the motherboard is designed with IPMI in mind. For whatever reason, it's enabled on my laptop despite it obviously not having IPMI support :)
- cozzyd 9mo ago
  https://www.freedesktop.org/software/systemd/man/latest/systemd-system.conf.html?__goaway_challenge=meta-refresh&__goaway_id=393f6aaea98836217f6c8267dc046ab9&__goaway_referer=https%3A%2F%2Fwww.google.com%2F#Hardware%20Watchdog https://www.freedesktop.org/software/systemd/man/latest/syst...
cat-whisperer 9mo ago
mac’s too?
- throwup238 9mo ago
  “All CPUs” would probably be 99.9999% accurate. It’s just one of those fundamental functions you want in a processor. Whether it’s exposed in the OS is a different matter.
  - LtdJorge 9mo ago
    AMD doesn't have it. I just confirmed by grepping through dmesg and journalctl -b, the only time it appears is due to UPS driver notifications (unrelated).
- inferiorhuman 9mo ago
  Cortex-A includes a watchdog so yeah.
lgas 9mo ago
That's a software watchdog. The comment you're replying to is talking about hardware watchdogs.

LtdJorge 9mo ago

Yes, but those are done in software

p_l 9mo ago
There's generally at least one watchdog device available in most PCs delivered in last decade, but it's not always utilized. Essentially at one point an intel southbridge integrated a basic watchdog on all models, and it started to just... be included. So these days you can find a variation on the TCO timer watchdog in most PCs, even if the exact implementation varies so we now have a bunch of drivers for the different variants.
- VorpalWay 9mo ago
  Linux doesn't see one on my Ryzen 5600X desktop at least. My Intel Skylake Thinkpad does seem to have two though (iTCO as well as INT3F0D, not sure what that is, but if I interpret the files under /sys correctly it belongs to the LPC/eSPI controller PCIe device, while the TCO watchdog is found under the SMBus PCIe device). In both cases they do have software watchdogs (NMI based) which relies on a hardware timer triggering an NMI in the kernel. But that relies on the NMI handler still working, which is not as good as a real HW watchdog.
  - p_l 9mo ago
    Apparently it depends to a little bit on how the motherboard is designed, theoretically SP5100 watchdog which is part of the CPU logic in recent ryzens, apparently, is supposed to be enabled if the motherboard is designed with IPMI in mind. For whatever reason, it's enabled on my laptop despite it obviously not having IPMI support :)
cozzyd 9mo ago
https://www.freedesktop.org/software/systemd/man/latest/systemd-system.conf.html?__goaway_challenge=meta-refresh&__goaway_id=393f6aaea98836217f6c8267dc046ab9&__goaway_referer=https%3A%2F%2Fwww.google.com%2F#Hardware%20Watchdog https://www.freedesktop.org/software/systemd/man/latest/syst...

cat-whisperer 9mo ago

mac’s too?

throwup238 9mo ago
“All CPUs” would probably be 99.9999% accurate. It’s just one of those fundamental functions you want in a processor. Whether it’s exposed in the OS is a different matter.
- LtdJorge 9mo ago
  AMD doesn't have it. I just confirmed by grepping through dmesg and journalctl -b, the only time it appears is due to UPS driver notifications (unrelated).
inferiorhuman 9mo ago
Cortex-A includes a watchdog so yeah.

lgas 9mo ago

That's a software watchdog. The comment you're replying to is talking about hardware watchdogs.