tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1.. SPDX-License-Identifier: GPL-2.0
2
3=========
4S/390 PCI
5=========
6
7Authors:
8 - Pierre Morel
9
10Copyright, IBM Corp. 2020
11
12
13Command line parameters and debugfs entries
14===========================================
15
16Command line parameters
17-----------------------
18
19* nomio
20
21 Do not use PCI Mapped I/O (MIO) instructions.
22
23* norid
24
25 Ignore the RID field and force use of one PCI domain per PCI function.
26
27debugfs entries
28---------------
29
30The S/390 debug feature (s390dbf) generates views to hold various debug results in sysfs directories of the form:
31
32 * /sys/kernel/debug/s390dbf/pci_*/
33
34For example:
35
36 - /sys/kernel/debug/s390dbf/pci_msg/sprintf
37 Holds messages from the processing of PCI events, like machine check handling
38 and setting of global functionality, like UID checking.
39
40 Change the level of logging to be more or less verbose by piping
41 a number between 0 and 6 to /sys/kernel/debug/s390dbf/pci_*/level. For
42 details, see the documentation on the S/390 debug feature at
43 Documentation/s390/s390dbf.rst.
44
45Sysfs entries
46=============
47
48Entries specific to zPCI functions and entries that hold zPCI information.
49
50* /sys/bus/pci/slots/XXXXXXXX
51
52 The slot entries are set up using the function identifier (FID) of the
53 PCI function. The format depicted as XXXXXXXX above is 8 hexadecimal digits
54 with 0 padding and lower case hexadecimal digitis.
55
56 - /sys/bus/pci/slots/XXXXXXXX/power
57
58 A physical function that currently supports a virtual function cannot be
59 powered off until all virtual functions are removed with:
60 echo 0 > /sys/bus/pci/devices/XXXX:XX:XX.X/sriov_numvf
61
62* /sys/bus/pci/devices/XXXX:XX:XX.X/
63
64 - function_id
65 A zPCI function identifier that uniquely identifies the function in the Z server.
66
67 - function_handle
68 Low-level identifier used for a configured PCI function.
69 It might be useful for debuging.
70
71 - pchid
72 Model-dependent location of the I/O adapter.
73
74 - pfgid
75 PCI function group ID, functions that share identical functionality
76 use a common identifier.
77 A PCI group defines interrupts, IOMMU, IOTLB, and DMA specifics.
78
79 - vfn
80 The virtual function number, from 1 to N for virtual functions,
81 0 for physical functions.
82
83 - pft
84 The PCI function type
85
86 - port
87 The port corresponds to the physical port the function is attached to.
88 It also gives an indication of the physical function a virtual function
89 is attached to.
90
91 - uid
92 The user identifier (UID) may be defined as part of the machine
93 configuration or the z/VM or KVM guest configuration. If the accompanying
94 uid_is_unique attribute is 1 the platform guarantees that the UID is unique
95 within that instance and no devices with the same UID can be attached
96 during the lifetime of the system.
97
98 - uid_is_unique
99 Indicates whether the user identifier (UID) is guaranteed to be and remain
100 unique within this Linux instance.
101
102 - pfip/segmentX
103 The segments determine the isolation of a function.
104 They correspond to the physical path to the function.
105 The more the segments are different, the more the functions are isolated.
106
107Enumeration and hotplug
108=======================
109
110The PCI address consists of four parts: domain, bus, device and function,
111and is of this form: DDDD:BB:dd.f
112
113* When not using multi-functions (norid is set, or the firmware does not
114 support multi-functions):
115
116 - There is only one function per domain.
117
118 - The domain is set from the zPCI function's UID as defined during the
119 LPAR creation.
120
121* When using multi-functions (norid parameter is not set),
122 zPCI functions are addressed differently:
123
124 - There is still only one bus per domain.
125
126 - There can be up to 256 functions per bus.
127
128 - The domain part of the address of all functions for
129 a multi-Function device is set from the zPCI function's UID as defined
130 in the LPAR creation for the function zero.
131
132 - New functions will only be ready for use after the function zero
133 (the function with devfn 0) has been enumerated.