Solution Found: Disable GPE 0x6F After months of living with this bug, I finally found a targeted fix that resolves the 100% CPU usage without breaking sound or any other functionality.
Root cause: GPE (General Purpose Event) 0x6F fires continuously because the BIOS fan status method \_SB.PC00.LPCB.H_EC.TFN1._FST references a symbol CFSP that doesn't exist in the ACPI tables. Each failed call triggers another interrupt, creating the storm visible in /proc/interrupts (113+ million hits on IRQ 9). Diagnosis: # Check which GPE is responsible for the storm: cat /sys/firmware/acpi/interrupts/gpe_all # shows millions cat /sys/firmware/acpi/interrupts/gpe6F # same number = culprit Immediate fix (no reboot needed): echo "disable" | sudo tee /sys/firmware/acpi/interrupts/gpe6F CPU usage drops to normal instantly. Sound, EC, keyboard, trackpad, everything else works fine. GPE 0x6E (the EC) is unaffected. Permanent fix (survives reboot): Create /etc/systemd/system/disable-gpe6f.service: [Unit] Description=Disable ACPI GPE 0x6F (broken fan status on Asus ExpertBook P3605CVA) After=sysinit.target [Service] Type=oneshot ExecStart=/bin/bash -c 'echo "disable" > /sys/firmware/acpi/interrupts/gpe6F' [Install] WantedBy=multi-user.target Then enable it: sudo systemctl daemon-reload sudo systemctl enable disable-gpe6f.service Environment: Kernel 6.18.7 on Ubuntu, but this should work on any kernel version since the issue is in the ASUS BIOS ACPI tables (P3605CVA BIOS version 302). Note: The proper fix would be for ASUS to release a BIOS update that defines the missing CFSP symbol, or for the kernel to handle the AE_NOT_FOUND error more gracefully instead of letting the GPE re-fire indefinitely. Until then, disabling GPE 0x6F is a clean workaround with no side effects. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2126636 Title: ACPI interrupt storm on Asus [Your Exact Laptop Model] causes 100% CPU, `acpi=noirq` workaround breaks audio To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2126636/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
