** Description changed:
[Impact]
On SBSA platforms, UEFI firmware may enable the hardware watchdog during
early boot and disable it at ExitBootServices. This leaves a watchdog
protection gap between firmware handoff and userspace watchdog daemon
startup.
[Fix]
Backport linux-next commit 11f93e639d513cbfaa78237cd163039d27fea33c
("watchdog: sbsa_gwdt: add early_enable module parameter"). It adds the
opt-in sbsa_gwdt.early_enable parameter. When enabled and firmware left
the watchdog disabled, the driver starts it during probe and marks it as
hardware-running so the watchdog core can issue pre-userspace
keepalives.
The parameter defaults to 0, preserving existing behavior.
Upstream submission:
https://patch.msgid.link/[email protected]
NV-Kernels PR: https://github.com/NVIDIA/NV-Kernels/pull/557
- [Test Plan]
-
- 1. Build linux-nvidia packages for amd64 and arm64.
- 2. On an SBSA platform whose firmware leaves the watchdog disabled, boot with
sbsa_gwdt.early_enable=1 and confirm the watchdog is running.
- 3. Delay userspace takeover beyond one heartbeat and confirm the watchdog
core keeps the system alive until the userspace daemon opens the watchdog
device.
- 4. Confirm early_enable=0 does not start a previously disabled watchdog.
- 5. Confirm an already-running firmware watchdog remains running.
-
[Where problems could occur]
The new behavior is opt-in and limited to the SBSA Generic Watchdog
driver. If early_enable is used while watchdog.handle_boot_enabled is
disabled, the kernel will not schedule pre-userspace keepalives and the
system may reset. Probe-failure and driver-unbind paths should also be
validated after an early start.
--
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/2166165
Title:
Backport watchdog: sbsa_gwdt: add early_enable module parameter
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux-nvidia/+bug/2166165/+subscriptions
--
ubuntu-bugs mailing list
[email protected]
https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
