forked from Minki/linux
9056754f65
Clarify the documentation. Signed-off-by: Pierre Morel <pmorel@linux.ibm.com> Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
126 lines
3.4 KiB
ReStructuredText
126 lines
3.4 KiB
ReStructuredText
.. 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.
|
|
|
|
- /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 debuging.
|
|
|
|
- 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 unique identifier (UID) is defined when configuring an LPAR and is
|
|
unique in the LPAR.
|
|
|
|
- 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.
|