watchdog: wdat_wdt: map registers that fall inside ACPI NVS - #270
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Some firmwares describe WDAT registers inside memory ranges marked as ACPI NVS in the E820 map, failing with -EBUSY during probe, leaving the hardware watchdog unserviced and triggering periodic system resets. This issue was observed on a OnLogic Karbon 524 device (when watchdog is enabled in BIOS): wdat_wdt wdat_wdt: error -EBUSY: can't request region for resource [mem 0x63df7a98] wdat_wdt wdat_wdt: probe with driver wdat_wdt failed with error -16 Check whether the region falls inside ACPI NVS before requesting it and, if so, map it without reservation. Signed-off-by: Renê de Souza Pinto <rene@renesp.com.br>
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Description
Some firmwares describe WDAT registers inside memory ranges marked as ACPI NVS in the E820 map, failing with -EBUSY during probe, leaving the hardware watchdog unserviced and triggering periodic system resets.
This issue was observed on a OnLogic Karbon 524 device (when watchdog is enabled in BIOS):
wdat_wdt wdat_wdt: error -EBUSY: can't request region for resource [mem 0x63df7a98]
wdat_wdt wdat_wdt: probe with driver wdat_wdt failed with error -16
Check whether the region falls inside ACPI NVS before requesting it and, if so, map it without reservation.
Upstream patch: https://lore.kernel.org/linux-watchdog/20260804094057.C71951F000E9@smtp.kernel.org/T/#t
Backports
For now only on this version since we don't use any ACPI watchdog on arm64. If the upstream got approved and can backport to other versions.