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s390/pci: Documentation update for s390 PCI

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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>
This commit is contained in:
Pierre Morel
2020-04-30 04:02:17 -04:00
committed by Vasily Gorbik
parent d1379279f2
commit 9056754f65
1 changed files with 41 additions and 42 deletions
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83
Documentation/s390/pci.rst
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@@ -10,7 +10,7 @@ Authors:
Copyright, IBM Corp. 2020 Copyright, IBM Corp. 2020
command line parameters and debugfs entries Command line parameters and debugfs entries
=========================================== ===========================================
Command line parameters Command line parameters
@@ -18,7 +18,7 @@ Command line parameters
* nomio * nomio
Do not use MIO instructions. Do not use PCI Mapped I/O (MIO) instructions.
* norid * norid
@@ -27,100 +27,99 @@ Command line parameters
debugfs entries debugfs entries
--------------- ---------------
* /sys/kernel/debug/s390dbf/pci_*/ (S/390 debug feature) The S/390 debug feature (s390dbf) generates views to hold various debug results in sysfs directories of the form:
Some views generated by the debug feature to hold various debug outputs. * /sys/kernel/debug/s390dbf/pci_*/
For example:
- /sys/kernel/debug/s390dbf/pci_msg/sprintf - /sys/kernel/debug/s390dbf/pci_msg/sprintf
Messages from the processing of PCI events like machine check handling Holds messages from the processing of PCI events, like machine check handling
and setting of global functionality like UID checking. and setting of global functionality, like UID checking.
The level of logging can be changed to be more or less verbose by piping to Change the level of logging to be more or less verbose by piping
/sys/kernel/debug/s390dbf/pci_*/level a number between 0 and 6; see the a number between 0 and 6 to /sys/kernel/debug/s390dbf/pci_*/level. For
documentation on the S/390 debug feature (Documentation/s390/s390dbf.rst) details, see the documentation on the S/390 debug feature at
for details. Documentation/s390/s390dbf.rst.
Sysfs entries Sysfs entries
============= =============
Specific entries, or entries specificities for zPCI functions. Entries specific to zPCI functions and entries that hold zPCI information.
* /sys/bus/pci/slots/XXXXXXXX * /sys/bus/pci/slots/XXXXXXXX
The slot entries are setup using the FID (Function Identifier) of the The slot entries are set up using the function identifier (FID) of the
PCI function. PCI function.
- /sys/bus/pci/slots/XXXXXXXX/power - /sys/bus/pci/slots/XXXXXXXX/power
A physical function currently supporting virtual function can not be A physical function that currently supports a virtual function cannot be
powered-off until all virtual-function have been removed with powered off until all virtual functions are removed with:
echo 0 > /sys/bus/pci/devices/XXXX:XX:XX.X/sriov_numvf echo 0 > /sys/bus/pci/devices/XXXX:XX:XX.X/sriov_numvf
* /sys/bus/pci/devices/XXXX:XX:XX.X/ * /sys/bus/pci/devices/XXXX:XX:XX.X/
- function_id - function_id
zPCI function identifier unique for the complete Z System. A zPCI function identifier that uniquely identifies the function in the Z server.
It define uniquely a function in the system.
- function_handle - function_handle
Low level identifier used for a configured PCI function. Low-level identifier used for a configured PCI function.
It may be useful for debuging. It might be useful for debuging.
- pchid - pchid
Model dependent location of the I/O adapter. Model-dependent location of the I/O adapter.
- pfgid - pfgid
PCI Function Group ID, functions sharing identical functionality PCI function group ID, functions that share identical functionality
are using a common identifier. use a common identifier.
A PCI group defines interrupts, IOMMU, IOTLB and DMA specifics. A PCI group defines interrupts, IOMMU, IOTLB, and DMA specifics.
- vfn - vfn
The Virtual Function Number, from 1 to N for virtual functions. The virtual function number, from 1 to N for virtual functions,
0 for physical functions. 0 for physical functions.
- pft - pft
PCI function type specifies the type of the PCI function. The PCI function type
- port - port
The port correspond to the physical port the function is attached to. The port corresponds to the physical port the function is attached to.
It also gives an indication on the physical function a virtual function It also gives an indication of the physical function a virtual function
is attached to. is attached to.
- uid - uid
The UID, Unique Identifier is defined when configuring a LPAR and is The unique identifier (UID) is defined when configuring an LPAR and is
unique inside an LPAR. unique in the LPAR.
- pfip/segmentX - pfip/segmentX
The segments are used to determine the isolation of a function. The segments determine the isolation of a function.
They corresponds to the physical path to the function. They correspond to the physical path to the function.
The more the segment are different the more the functions are isolated. The more the segments are different, the more the functions are isolated.
Enumeration and hotplug Enumeration and hotplug
======================= =======================
The PCI address is made of 4 parts: domain, bus, device and function, The PCI address consists of four parts: domain, bus, device and function,
like in DDDD:BB:dd.f and is of this form: DDDD:BB:dd.f
* When not using multi-functions (norid is set or firmware does not support * When not using multi-functions (norid is set, or the firmware does not
multi-functions) support multi-functions):
- There is only one function per domain. - There is only one function per domain.
- the domain is set from the zPCI function's UID as defined during the - The domain is set from the zPCI function's UID as defined during the
LPAR creation. LPAR creation.
- Addresses look like DDDD:00:00.0 * When using multi-functions (norid parameter is not set),
zPCI functions are addressed differently:
* When using multi-functions (norid parameter is not set), there are some
change in the way zPCI functions are addressed:
- There is still only one bus per domain. - There is still only one bus per domain.
- There can be up to 256 functions per bus. - There can be up to 256 functions per bus.
- The domain part of the address of all functions of all functions for - The domain part of the address of all functions for
a multi-Function device is set from the zPCI function's UID as defined a multi-Function device is set from the zPCI function's UID as defined
in the LPAR creation for the function zero. in the LPAR creation for the function zero.
- New functions will only be ready to be used after the function zero - New functions will only be ready for use after the function zero
(the function with devfn 0) has been enumerated. (the function with devfn 0) has been enumerated.