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-rw-r--r--Documentation/admin-guide/kernel-parameters.txt32
1 files changed, 32 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 500cfa776225..b2057241ea6c 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4619,6 +4619,38 @@
bridges without forcing it upstream. Note:
this removes isolation between devices and
may put more devices in an IOMMU group.
+ config_acs=
+ Format:
+ <ACS flags>@<pci_dev>[; ...]
+ Specify one or more PCI devices (in the format
+ specified above) optionally prepended with flags
+ and separated by semicolons. The respective
+ capabilities will be enabled, disabled or
+ unchanged based on what is specified in
+ flags.
+
+ ACS Flags is defined as follows:
+ bit-0 : ACS Source Validation
+ bit-1 : ACS Translation Blocking
+ bit-2 : ACS P2P Request Redirect
+ bit-3 : ACS P2P Completion Redirect
+ bit-4 : ACS Upstream Forwarding
+ bit-5 : ACS P2P Egress Control
+ bit-6 : ACS Direct Translated P2P
+ Each bit can be marked as:
+ '0' – force disabled
+ '1' – force enabled
+ 'x' – unchanged
+ For example,
+ pci=config_acs=10x
+ would configure all devices that support
+ ACS to enable P2P Request Redirect, disable
+ Translation Blocking, and leave Source
+ Validation unchanged from whatever power-up
+ or firmware set it to.
+
+ Note: this may remove isolation between devices
+ and may put more devices in an IOMMU group.
force_floating [S390] Force usage of floating interrupts.
nomio [S390] Do not use MIO instructions.
norid [S390] ignore the RID field and force use of