Public bug reported:
[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.
** Affects: linux-nvidia (Ubuntu)
Importance: Undecided
Status: New
** Tags: kernel-daily-bug
--
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
