AxlWatchdog — boot-services watchdog

Wrapper for gBS->SetWatchdogTimer (UEFI 2.11 §7.5). UEFI starts every loaded image with a 5-minute boot-services watchdog armed; long-running diagnostics need to disarm or extend the timer or they’re killed without warning.

API Reference

Boot-services watchdog timer.

UEFI starts every loaded image with a 5-minute boot-services watchdog armed (UEFI 2.11 §7.5). If the image hasn’t called Exit() or disarmed the timer within that window the firmware resets the system. Long-running diagnostics get killed without warning unless they take action; this module is the typed wrapper for that.

// Run diagnostics that may exceed 5 minutes.
axl_watchdog_disarm();

// Or extend the budget without disabling protection entirely.
axl_watchdog_set(900);   // 15 minutes

Functions

int axl_watchdog_disarm(void)

Disarm the boot-services watchdog.

Equivalent to axl_watchdog_set(0). After this call, the firmware will not reset the image for failing to make progress.

Returns:: 0 on success, -1 if the firmware refuses (rare).

int axl_watchdog_set(uint64_t seconds)

Arm or extend the boot-services watchdog.

seconds == 0 disarms (same as axl_watchdog_disarm). Otherwise the firmware resets the system after seconds elapse without another call to this function or to Exit(). Each call replaces the prior timeout.

The internal “last set” value is remembered for axl_watchdog_pet.

Parameters:

seconds – new timeout in seconds; 0 disarms

Returns:

0 on success, -1 on failure.

int axl_watchdog_pet(void)

Re-arm the watchdog to the value last passed to axl_watchdog_set.

Convenient for “feed the dog” loops where the same window is extended periodically. If axl_watchdog_set has not been called yet this session, _pet is a no-op and returns 0.

Returns:: 0 on success, -1 on failure.