Copyright, IBM Corp. 2020
Command line parameters and debugfs entries¶
Command line parameters¶
Do not use PCI Mapped I/O (MIO) instructions.
Ignore the RID field and force use of one PCI domain per PCI function.
The S/390 debug feature (s390dbf) generates views to hold various debug results in sysfs directories of the form:
/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.
Entries specific to zPCI functions and entries that hold zPCI information.
The slot entries are set up using the function identifier (FID) of the PCI function.
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
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.