+++ /dev/null
-.. SPDX-License-Identifier: GPL-2.0
-
-=========
-S/390 PCI
-=========
-
-Authors:
- - Pierre Morel
-
-Copyright, IBM Corp. 2020
-
-
-Command line parameters and debugfs entries
-===========================================
-
-Command line parameters
------------------------
-
-* nomio
-
- Do not use PCI Mapped I/O (MIO) instructions.
-
-* norid
-
- Ignore the RID field and force use of one PCI domain per PCI function.
-
-debugfs entries
----------------
-
-The S/390 debug feature (s390dbf) generates views to hold various debug results in sysfs directories of the form:
-
- * /sys/kernel/debug/s390dbf/pci_*/
-
-For example:
-
- - /sys/kernel/debug/s390dbf/pci_msg/sprintf
- Holds messages from the processing of PCI events, like machine check handling
- and setting of global functionality, like UID checking.
-
- Change the level of logging to be more or less verbose by piping
- a number between 0 and 6 to /sys/kernel/debug/s390dbf/pci_*/level. For
- details, see the documentation on the S/390 debug feature at
- Documentation/s390/s390dbf.rst.
-
-Sysfs entries
-=============
-
-Entries specific to zPCI functions and entries that hold zPCI information.
-
-* /sys/bus/pci/slots/XXXXXXXX
-
- The slot entries are set up using the function identifier (FID) of the
- PCI function. The format depicted as XXXXXXXX above is 8 hexadecimal digits
- with 0 padding and lower case hexadecimal digits.
-
- - /sys/bus/pci/slots/XXXXXXXX/power
-
- A physical function that currently supports a virtual function cannot be
- powered off until all virtual functions are removed with:
- echo 0 > /sys/bus/pci/devices/XXXX:XX:XX.X/sriov_numvf
-
-* /sys/bus/pci/devices/XXXX:XX:XX.X/
-
- - function_id
- A zPCI function identifier that uniquely identifies the function in the Z server.
-
- - function_handle
- Low-level identifier used for a configured PCI function.
- It might be useful for debugging.
-
- - pchid
- Model-dependent location of the I/O adapter.
-
- - pfgid
- PCI function group ID, functions that share identical functionality
- use a common identifier.
- A PCI group defines interrupts, IOMMU, IOTLB, and DMA specifics.
-
- - vfn
- The virtual function number, from 1 to N for virtual functions,
- 0 for physical functions.
-
- - pft
- The PCI function type
-
- - port
- The port corresponds to the physical port the function is attached to.
- It also gives an indication of the physical function a virtual function
- is attached to.
-
- - uid
- The user identifier (UID) may be defined as part of the machine
- configuration or the z/VM or KVM guest configuration. If the accompanying
- uid_is_unique attribute is 1 the platform guarantees that the UID is unique
- within that instance and no devices with the same UID can be attached
- during the lifetime of the system.
-
- - uid_is_unique
- Indicates whether the user identifier (UID) is guaranteed to be and remain
- unique within this Linux instance.
-
- - pfip/segmentX
- The segments determine the isolation of a function.
- They correspond to the physical path to the function.
- The more the segments are different, the more the functions are isolated.
-
-Enumeration and hotplug
-=======================
-
-The PCI address consists of four parts: domain, bus, device and function,
-and is of this form: DDDD:BB:dd.f
-
-* When not using multi-functions (norid is set, or the firmware does not
- support multi-functions):
-
- - There is only one function per domain.
-
- - The domain is set from the zPCI function's UID as defined during the
- LPAR creation.
-
-* When using multi-functions (norid parameter is not set),
- zPCI functions are addressed differently:
-
- - There is still only one bus per domain.
-
- - There can be up to 256 functions per bus.
-
- - The domain part of the address of all functions for
- a multi-Function device is set from the zPCI function's UID as defined
- in the LPAR creation for the function zero.
-
- - New functions will only be ready for use after the function zero
- (the function with devfn 0) has been enumerated.
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