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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
commit | 5d1646d90e1f2cceb9f0828f4b28318cd0ec7744 (patch) | |
tree | a94efe259b9009378be6d90eb30d2b019d95c194 /Documentation/s390/pci.rst | |
parent | Initial commit. (diff) | |
download | linux-upstream/5.10.209.tar.xz linux-upstream/5.10.209.zip |
Adding upstream version 5.10.209.upstream/5.10.209upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | Documentation/s390/pci.rst | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/Documentation/s390/pci.rst b/Documentation/s390/pci.rst new file mode 100644 index 000000000..492850bff --- /dev/null +++ b/Documentation/s390/pci.rst @@ -0,0 +1,125 @@ +.. 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. |