From 7ece14175376051b18a9b97f0e6125cb8b864155 Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Tue, 6 Sep 2016 16:24:37 -0500 Subject: PCI/AER: Remove aerdriver.forceload kernel parameter Per the PCI Firmware spec, r3.0, sec 4.5.1, on ACPI systems, the OS must not use AER unless _OSC is present and _OSC grants AER control to the OS. The aerdriver.forceload kernel parameter was a way to enable Linux AER support on ACPI systems that lack _OSC or fail to grant control the the OS. Enabling Linux AER support when the firmware doesn't want us to is a recipe for problems, e.g., the firmware might be handling AER itself. Remove the aerdriver.forceload kernel parameter and related supporting code. Signed-off-by: Bjorn Helgaas --- Documentation/PCI/pcieaer-howto.txt | 22 +++++++++------------- 1 file changed, 9 insertions(+), 13 deletions(-) (limited to 'Documentation/PCI') diff --git a/Documentation/PCI/pcieaer-howto.txt b/Documentation/PCI/pcieaer-howto.txt index 4956df36c59d..ea8cafba255c 100644 --- a/Documentation/PCI/pcieaer-howto.txt +++ b/Documentation/PCI/pcieaer-howto.txt @@ -49,21 +49,17 @@ depends on CONFIG_PCIEPORTBUS, so pls. set CONFIG_PCIEPORTBUS=y and CONFIG_PCIEAER = y. 2.2 Load PCI Express AER Root Driver -There is a case where a system has AER support in BIOS. Enabling the AER -Root driver and having AER support in BIOS may result unpredictable -behavior. To avoid this conflict, a successful load of the AER Root driver -requires ACPI _OSC support in the BIOS to allow the AER Root driver to -request for native control of AER. See the PCI FW 3.0 Specification for -details regarding OSC usage. Currently, lots of firmwares don't provide -_OSC support while they use PCI Express. To support such firmwares, -forceload, a parameter of type bool, could enable AER to continue to -be initiated although firmwares have no _OSC support. To enable the -walkaround, pls. add aerdriver.forceload=y to kernel boot parameter line -when booting kernel. Note that forceload=n by default. + +Some systems have AER support in firmware. Enabling Linux AER support at +the same time the firmware handles AER may result in unpredictable +behavior. Therefore, Linux does not handle AER events unless the firmware +grants AER control to the OS via the ACPI _OSC method. See the PCI FW 3.0 +Specification for details regarding _OSC usage. 2.3 AER error output -When a PCI-E AER error is captured, an error message will be outputted to -console. If it's a correctable error, it is outputted as a warning. + +When a PCIe AER error is captured, an error message will be output to +console. If it's a correctable error, it is output as a warning. Otherwise, it is printed as an error. So users could choose different log level to filter out correctable error messages. -- cgit