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| author | Yijing Wang <wangyijing@huawei.com> | 2013-01-30 09:40:52 +0800 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2013-01-31 09:09:32 -0700 |
| commit | fa2387124b1ac8177f7af33668ec98135fdd147f (patch) | |
| tree | c5ac79ba9386e23b16597d22aefd4552c8d1b2f0 /Documentation/kernel-parameters.txt | |
| parent | 8c8803c5968bd82ad3d65e8603c6bcf2d9674d83 (diff) | |
| download | lwn-fa2387124b1ac8177f7af33668ec98135fdd147f.tar.gz lwn-fa2387124b1ac8177f7af33668ec98135fdd147f.zip | |
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>
Diffstat (limited to 'Documentation/kernel-parameters.txt')
| -rw-r--r-- | Documentation/kernel-parameters.txt | 15 |
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. |