Environment
Board: Radxa Cubie A7S
SoC: Allwinner A733 (T527)
Kernel: 5.15.147-18-a733 #18 SMP PREEMPT
OS: Debian GNU/Linux 11 (bullseye), arm64
Cooling: Active (PWM fan), CPU temp ~50°C during lockup
Description
The board experiences a hard lockup after approximately 20 minutes of sustained full CPU load across all 8 cores (6× Cortex-A55 + 2× Cortex-A76). The system becomes completely unresponsive — no ping, no SSH — and requires a power cycle or is recovered automatically by the hardware watchdog (sunxi-wdt).
Notably, the lockup occurs at normal operating temperature (~50–52°C), ruling out thermal shutdown as the cause. There is no OOM killer activity and no kernel panic recorded in the journal. The hardware watchdog silently resets the board.
A secondary issue is present: systemd reports a failure when attempting to configure the sunxi-wdt timeout, suggesting the watchdog driver does not correctly handle the requested timeout value.
Steps to reproduce
- Boot the board with adequate cooling (fan running, CPU temp ~35°C at idle)
- Run a sustained multi-core CPU stress workload, e.g.:
sudo sbc-bench.sh -r or 7zr b -mmt8
- Wait approximately 15–25 minutes with all 8 cores at 100% load
- Board becomes unresponsive (no ping, no SSH)
- no automatic reboot from watchdog
Expected behavior
Board should remain stable indefinitely under full CPU load at normal operating temperatures. If a watchdog is used, its timeout should be configurable without error.
Actual behavior
Board locks up hard after ~20 minutes. The hardware watchdog (sunxi-wdt) don't reset the system. No panic, no OOM, no thermal event — clean watchdog reset with no root cause logged.
Relevant log output (journalctl -b -1)
Apr 17 22:26:23 radxa-cubie-a7s systemd[1]: Using hardware watchdog 'sunxi-wdt', version 0, device /dev/watchdog
Apr 17 22:26:23 radxa-cubie-a7s systemd[1]: Failed to set timeout to 600s: Invalid argument
Apr 17 22:26:24 radxa-cubie-a7s systemd-shutdown[1]: Syncing filesystems and block devices.
Apr 17 22:26:24 radxa-cubie-a7s systemd-shutdown[1]: Sending SIGTERM to remaining processes...
Apr 17 22:26:24 radxa-cubie-a7s systemd-journald[274]: Journal stopped
No kernel panic, no OOM killer, no thermal trip in logs before shutdown.
dmesg grep for panic|lockup|hung|oom|killed returned no results.
CPU state at time of lockup
Frequency: 1404–1508 MHz (A55) / 1196–1404 MHz (A76) — normal operation
Temperature: ~51°C (cpub_idle_zone) — well below trip points
Load: 100% all 8 cores
Duration: ~20 minutes of sustained load
Secondary issue: sunxi-wdt timeout configuration failure
systemd[1]: Failed to set timeout to 600s: Invalid argument
The sunxi-wdt driver rejects the timeout value requested by systemd. This may indicate an incorrect maximum timeout value exposed by the driver, or a missing implementation of the timeout-set ioctl for this SoC variant.
Additional notes
— Power supply: 5V/3A, measured current draw ~900mA peak under full load (well within limits)
— A related issue has been filed separately: CPU thermal throttling not released after cooldown (frequency stuck at 416 MHz)
— Both issues observed on kernel 5.15.147-18-a733, no other kernels tested
Environment
Board: Radxa Cubie A7S
SoC: Allwinner A733 (T527)
Kernel: 5.15.147-18-a733 #18 SMP PREEMPT
OS: Debian GNU/Linux 11 (bullseye), arm64
Cooling: Active (PWM fan), CPU temp ~50°C during lockup
Description
The board experiences a hard lockup after approximately 20 minutes of sustained full CPU load across all 8 cores (6× Cortex-A55 + 2× Cortex-A76). The system becomes completely unresponsive — no ping, no SSH — and requires a power cycle or is recovered automatically by the hardware watchdog (sunxi-wdt).
Notably, the lockup occurs at normal operating temperature (~50–52°C), ruling out thermal shutdown as the cause. There is no OOM killer activity and no kernel panic recorded in the journal. The hardware watchdog silently resets the board.
A secondary issue is present: systemd reports a failure when attempting to configure the sunxi-wdt timeout, suggesting the watchdog driver does not correctly handle the requested timeout value.
Steps to reproduce
sudo sbc-bench.sh -r or 7zr b -mmt8
Expected behavior
Board should remain stable indefinitely under full CPU load at normal operating temperatures. If a watchdog is used, its timeout should be configurable without error.
Actual behavior
Board locks up hard after ~20 minutes. The hardware watchdog (sunxi-wdt) don't reset the system. No panic, no OOM, no thermal event — clean watchdog reset with no root cause logged.
Relevant log output (journalctl -b -1)
Apr 17 22:26:23 radxa-cubie-a7s systemd[1]: Using hardware watchdog 'sunxi-wdt', version 0, device /dev/watchdog
Apr 17 22:26:23 radxa-cubie-a7s systemd[1]: Failed to set timeout to 600s: Invalid argument
Apr 17 22:26:24 radxa-cubie-a7s systemd-shutdown[1]: Syncing filesystems and block devices.
Apr 17 22:26:24 radxa-cubie-a7s systemd-shutdown[1]: Sending SIGTERM to remaining processes...
Apr 17 22:26:24 radxa-cubie-a7s systemd-journald[274]: Journal stopped
No kernel panic, no OOM killer, no thermal trip in logs before shutdown.
dmesg grep for panic|lockup|hung|oom|killed returned no results.
CPU state at time of lockup
Frequency: 1404–1508 MHz (A55) / 1196–1404 MHz (A76) — normal operation
Temperature: ~51°C (cpub_idle_zone) — well below trip points
Load: 100% all 8 cores
Duration: ~20 minutes of sustained load
Secondary issue: sunxi-wdt timeout configuration failure
systemd[1]: Failed to set timeout to 600s: Invalid argument
The sunxi-wdt driver rejects the timeout value requested by systemd. This may indicate an incorrect maximum timeout value exposed by the driver, or a missing implementation of the timeout-set ioctl for this SoC variant.
Additional notes
— Power supply: 5V/3A, measured current draw ~900mA peak under full load (well within limits)
— A related issue has been filed separately: CPU thermal throttling not released after cooldown (frequency stuck at 416 MHz)
— Both issues observed on kernel 5.15.147-18-a733, no other kernels tested