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Old 14th April 2011
elerdin elerdin is offline
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Hallo, I have an OpenBSD4.8 installed on a Intel Atom D410 motherboard, I want to enable watchdog, the mobo should have hardware timer, but I cannot enable it in the bios. For linux there is a software watchdog, but is for linux only, is there something similar for openbsd?

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Old 14th April 2011
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OpenBSD's watchdog(4) uses the first available hardware watchdog timer. This is a hardware-only implementation, since at timeout, the BIOS reboots the platform. As I understand it, a "software watchdog timer" would require a running system, precluding a forced reboot in the event of a system crash.
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Old 14th April 2011
elerdin elerdin is offline
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Yes, I had the same idea, but I hoped I was wrong ;-) So I tried another way, I put to 0 the ddb.panic in sysconf, if I understood right this will force a reboot in case of kernel panic, is this right?

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Old 14th April 2011
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Right. In the event of a managed kernel panic, the kernel will attempt to dump RAM contents into swap space, and then reboot the system. This will work, if the kernel is still functioning.

The advantage of using a hardware watchdog timer -- if the hardware has one -- is that it acts as a dead man's switch so that hardware gets rebooted automatically if the kernel isn't communicating with the hardware regularly.
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Old 14th April 2011
elerdin elerdin is offline
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Well, next time I'll search a cheap motherboard that support watchdog timer (any suggestion is appeciated ;-))

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Old 14th April 2011
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This is most advantageous for remote servers, and one series of Dell server platforms with watchdog timers got a mention in 2005 in the OpenBSD Journal.

OpenBSD/i386 has some hardware listed as officially supported:
Quote:
  • AMD Elan SC520 System Controller (elansc) (G)
  • ICS PCI-WDT500/501 watchdog timer (wdt) (G)
  • Intel 6300ESB ICH (ichwdt) (*)
  • National Semiconductor Geode SC1100 IAOC (geodesc) (*)
  • Quancom PWDOG1 watchdog timer (pwdog) (G)
  • VIA VT1211 (viasio) (G)
There's no list for amd64 or sparc64.
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Old 14th April 2011
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I'd say almost every system has a watchdog timer available, unfortunately drivers have to be written to take advantage of them.. usually it's a chipset feature (..southbridge), supported by the chipset driver.

However, there do exist some PCI cards.. berkwdt(4) was added a few releases ago, it's for Berkshire products.

A few of my systems have an it(4) device, this is a temperature sensor.. but it also includes a watchdog timer that the kernel can use.

One problem is that if the interval is too short, the system might reboot.. even if the kernel may have recovered within a few seconds, also, the filesystem is left in an inconsistent state and you can lose data.
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