## page was renamed from Kernel/Reference/fwts/aspm
== Firmware Test Suite - aspm test ==

ASPM is a power-saving protocol used in PCI Express. ASPM enablement can be configured by BIOS or by an OS. This test checks the enablement method in ACPI table and verifies the correctness of the ASPM configuration.

Example output from this test:

{{{
PCIe ASPM check.
----------------------------------------------------------------------------------------------------
Test 1 of 2: PCIe ASPM ACPI test.
PCIE ASPM is not controlled by Linux kernel.

ADVICE: BIOS reports that Linux kernel should not modify ASPM settings that BIOS configured. It can
be intentional because hardware vendors identified some capability bugs between the motherboard and
the add-on cards.


Test 2 of 2: PCIe ASPM registers test.
WARNING: Test 2, RP 00h:1Ch.01h L0s not enabled.
WARNING: Test 2, RP 00h:1Ch.01h L1 not enabled.
WARNING: Test 2, Device 03h:00h.00h L0s not enabled.
WARNING: Test 2, Device 03h:00h.00h L1 not enabled.

ADVICE: The ASPM L0s low power Link state is optimized for short entry and exit latencies, while
providing substantial power savings. Disabling L0s of a PCIe device may increases power consumption,
and will impact the battery life of a mobile system.


ADVICE: The ASPM L1 low power Link state is optimized for maximum power savings with longer entry
and exit latencies. Disabling L1 of a PCIe device may increases power consumption, and will impact
the battery life of a mobile system significantly.

PASSED: Test 2, PCIE aspm setting matched was matched.
}}}


=== Examples: ===

{{{sudo fwts aspm}}}

== Explanation of test results ==

Certain test results may require a little more explanation. This section will try and give some context to specific test failures.

||Error ID||Explanation||
||PCIEASPM_UNMATCHED||Unmatched configuration indicates the system is not saving power at its full potential.||