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authorBjorn Helgaas <bhelgaas@google.com>2016-09-07 00:24:37 +0300
committerBjorn Helgaas <bhelgaas@google.com>2016-09-14 23:27:49 +0300
commit7ece14175376051b18a9b97f0e6125cb8b864155 (patch)
treebcfcc5f761bf26b4356634c67e74bd9ae2e44163 /Documentation/PCI
parent9ff25e6b3eb0012297288dfa87930c7b62ef6ab1 (diff)
downloadlinux-7ece14175376051b18a9b97f0e6125cb8b864155.tar.xz
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 <bhelgaas@google.com>
Diffstat (limited to 'Documentation/PCI')
-rw-r--r--Documentation/PCI/pcieaer-howto.txt22
1 files changed, 9 insertions, 13 deletions
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.