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authorYijing Wang <wangyijing@huawei.com>2013-01-30 09:40:52 +0800
committerBjorn Helgaas <bhelgaas@google.com>2013-01-31 09:09:32 -0700
commitfa2387124b1ac8177f7af33668ec98135fdd147f (patch)
treec5ac79ba9386e23b16597d22aefd4552c8d1b2f0
parent8c8803c5968bd82ad3d65e8603c6bcf2d9674d83 (diff)
downloadlinux-fa2387124b1ac8177f7af33668ec98135fdd147f.tar.gz
PCI: Document MPS parameters pci=pcie_bus_safe, pci=pcie_bus_perf, etc
Document PCIe bus MPS parameters pcie_bus_tune_off, pcie_bus_safe, pcie_bus_peer2peer, pcie_bus_perf. These parameters were introduced by Jon Mason <jdmason@kudzu.us> at commit 5f39e6705 and commit b03e7495a8. [bhelgaas: mention hot-add for pcie_bus_peer2peer] Signed-off-by: Yijing Wang <wangyijing@huawei.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
-rw-r--r--Documentation/kernel-parameters.txt15
1 files changed, 15 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 69f97a836600..dd80599559a5 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2227,6 +2227,21 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
This sorting is done to get a device
order compatible with older (<= 2.4) kernels.
nobfsort Don't sort PCI devices into breadth-first order.
+ pcie_bus_tune_off Disable PCIe MPS (Max Payload Size)
+ tuning and use the BIOS-configured MPS defaults.
+ pcie_bus_safe Set every device's MPS to the largest value
+ supported by all devices below the root complex.
+ pcie_bus_perf Set device MPS to the largest allowable MPS
+ based on its parent bus. Also set MRRS (Max
+ Read Request Size) to the largest supported
+ value (no larger than the MPS that the device
+ or bus can support) for best performance.
+ pcie_bus_peer2peer Set every device's MPS to 128B, which
+ every device is guaranteed to support. This
+ configuration allows peer-to-peer DMA between
+ any pair of devices, possibly at the cost of
+ reduced performance. This also guarantees
+ that hot-added devices will work.
cbiosize=nn[KMG] The fixed amount of bus space which is
reserved for the CardBus bridge's IO window.
The default value is 256 bytes.