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| author | Logan Gunthorpe <logang@deltatee.com> | 2018-07-30 10:18:38 -0600 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2018-08-09 16:24:39 -0500 |
| commit | 45db33709ccc7330c55fc6751c96468de407f2ac (patch) | |
| tree | 157e69c9e097e133761083b632d1458ed0bd5464 /Documentation/admin-guide/kernel-parameters.txt | |
| parent | 07d8d7e57c28ca9a07dab4efd75dad3a654aeb85 (diff) | |
| download | lwn-45db33709ccc7330c55fc6751c96468de407f2ac.tar.gz lwn-45db33709ccc7330c55fc6751c96468de407f2ac.zip | |
PCI: Allow specifying devices using a base bus and path of devfns
When specifying PCI devices on the kernel command line using a
bus/device/function address, bus numbers can change when adding or
replacing a device, changing motherboard firmware, or applying kernel
parameters like "pci=assign-buses". When bus numbers change, it's likely
the command line tweak will be applied to the wrong device.
Therefore, it is useful to be able to specify devices with a base bus
number and the path of devfns needed to get to it, similar to the "device
scope" structure in the Intel VT-d spec, Section 8.3.1.
Thus, we add an option to specify devices in the following format:
[<domain>:]<bus>:<device>.<func>[/<device>.<func>]*
The path can be any segment within the PCI hierarchy of any length and
determined through the use of 'lspci -t'. When specified this way, it is
less likely that a renumbered bus will result in a valid device
specification and the tweak won't be applied to the wrong device.
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
[bhelgaas: use "device" instead of "slot" in documentation since that's the
usual language in the PCI specs]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Stephen Bates <sbates@raithlin.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Acked-by: Christian König <christian.koenig@amd.com>
Diffstat (limited to 'Documentation/admin-guide/kernel-parameters.txt')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index ab36fb34ed01..4fa4c9ff04ae 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3000,7 +3000,7 @@ or a set of devices (<pci_dev>). These are specified in one of the following formats: - [<domain>:]<bus>:<device>.<func> + [<domain>:]<bus>:<dev>.<func>[/<dev>.<func>]* pci:<vendor>:<device>[:<subvendor>:<subdevice>] Note: the first format specifies a PCI @@ -3009,7 +3009,11 @@ firmware changes, or due to changes caused by other kernel parameters. If the domain is left unspecified, it is - taken to be zero. The second format + taken to be zero. Optionally, a path + to a device through multiple device/function + addresses can be specified after the base + address (this is more robust against + renumbering issues). The second format selects devices using IDs from the configuration space which may match multiple devices in the system. |