pci.rst 3.4 KB

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  1. .. SPDX-License-Identifier: GPL-2.0
  2. =========
  3. S/390 PCI
  4. =========
  5. Authors:
  6. - Pierre Morel
  7. Copyright, IBM Corp. 2020
  8. Command line parameters and debugfs entries
  9. ===========================================
  10. Command line parameters
  11. -----------------------
  12. * nomio
  13. Do not use PCI Mapped I/O (MIO) instructions.
  14. * norid
  15. Ignore the RID field and force use of one PCI domain per PCI function.
  16. debugfs entries
  17. ---------------
  18. The S/390 debug feature (s390dbf) generates views to hold various debug results in sysfs directories of the form:
  19. * /sys/kernel/debug/s390dbf/pci_*/
  20. For example:
  21. - /sys/kernel/debug/s390dbf/pci_msg/sprintf
  22. Holds messages from the processing of PCI events, like machine check handling
  23. and setting of global functionality, like UID checking.
  24. Change the level of logging to be more or less verbose by piping
  25. a number between 0 and 6 to /sys/kernel/debug/s390dbf/pci_*/level. For
  26. details, see the documentation on the S/390 debug feature at
  27. Documentation/s390/s390dbf.rst.
  28. Sysfs entries
  29. =============
  30. Entries specific to zPCI functions and entries that hold zPCI information.
  31. * /sys/bus/pci/slots/XXXXXXXX
  32. The slot entries are set up using the function identifier (FID) of the
  33. PCI function.
  34. - /sys/bus/pci/slots/XXXXXXXX/power
  35. A physical function that currently supports a virtual function cannot be
  36. powered off until all virtual functions are removed with:
  37. echo 0 > /sys/bus/pci/devices/XXXX:XX:XX.X/sriov_numvf
  38. * /sys/bus/pci/devices/XXXX:XX:XX.X/
  39. - function_id
  40. A zPCI function identifier that uniquely identifies the function in the Z server.
  41. - function_handle
  42. Low-level identifier used for a configured PCI function.
  43. It might be useful for debuging.
  44. - pchid
  45. Model-dependent location of the I/O adapter.
  46. - pfgid
  47. PCI function group ID, functions that share identical functionality
  48. use a common identifier.
  49. A PCI group defines interrupts, IOMMU, IOTLB, and DMA specifics.
  50. - vfn
  51. The virtual function number, from 1 to N for virtual functions,
  52. 0 for physical functions.
  53. - pft
  54. The PCI function type
  55. - port
  56. The port corresponds to the physical port the function is attached to.
  57. It also gives an indication of the physical function a virtual function
  58. is attached to.
  59. - uid
  60. The unique identifier (UID) is defined when configuring an LPAR and is
  61. unique in the LPAR.
  62. - pfip/segmentX
  63. The segments determine the isolation of a function.
  64. They correspond to the physical path to the function.
  65. The more the segments are different, the more the functions are isolated.
  66. Enumeration and hotplug
  67. =======================
  68. The PCI address consists of four parts: domain, bus, device and function,
  69. and is of this form: DDDD:BB:dd.f
  70. * When not using multi-functions (norid is set, or the firmware does not
  71. support multi-functions):
  72. - There is only one function per domain.
  73. - The domain is set from the zPCI function's UID as defined during the
  74. LPAR creation.
  75. * When using multi-functions (norid parameter is not set),
  76. zPCI functions are addressed differently:
  77. - There is still only one bus per domain.
  78. - There can be up to 256 functions per bus.
  79. - The domain part of the address of all functions for
  80. a multi-Function device is set from the zPCI function's UID as defined
  81. in the LPAR creation for the function zero.
  82. - New functions will only be ready for use after the function zero
  83. (the function with devfn 0) has been enumerated.