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| author |   Niklas Schnelle <schnelle@linux.ibm.com> | 2021-02-24 11:29:36 +0100 |
|---|---|---|
| committer |   Heiko Carstens <hca@linux.ibm.com> | 2021-04-20 14:48:27 +0200 |
| commit | 81bbf03905aae47a80fd05604cc9b0d1ca20e30a (patch) | |
| tree | 3043a193866a502486c5fd3353ce2abdbc4e708a /Documentation/ABI | |
| parent | s390/atomic,cmpxchg: always inline __xchg/__cmpxchg (diff) | |
| download | linux-dev-81bbf03905aae47a80fd05604cc9b0d1ca20e30a.tar.xz linux-dev-81bbf03905aae47a80fd05604cc9b0d1ca20e30a.zip | |
s390/pci: expose a PCI device's UID as its index
On s390 each PCI device has a user-defined ID (UID) exposed under
/sys/bus/pci/devices/<dev>/uid. This ID was designed to serve as the PCI
device's primary index and to match the device within Linux to the
device configured in the hypervisor. To serve as a primary identifier
the UID must be unique within the Linux instance, this is guaranteed by
the platform if and only if the UID Uniqueness Checking flag is set
within the CLP List PCI Functions response.
In this sense the UID serves an analogous function as the SMBIOS
instance number or ACPI index exposed as the "index" respectively
"acpi_index" device attributes and used by e.g. systemd to set interface
names. As s390 does not use and will likely never use ACPI nor SMBIOS
there is no conflict and we can just expose the UID under the "index"
attribute whenever UID Uniqueness Checking is active and get systemd's
interface naming support for free.
Link: https://lore.kernel.org/lkml/20210412135905.1434249-1-schnelle@linux.ibm.com/
Acked-by: Viktor Mihajlovski <mihajlov@linux.ibm.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Narendra K <narendra_k@dell.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Diffstat (limited to 'Documentation/ABI')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-bus-pci | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci index 25c9c39770c6..1241b6d11a52 100644 --- a/Documentation/ABI/testing/sysfs-bus-pci +++ b/Documentation/ABI/testing/sysfs-bus-pci @@ -195,10 +195,13 @@ What: /sys/bus/pci/devices/.../index Date: July 2010 Contact: Narendra K <narendra_k@dell.com>, linux-bugs@dell.com Description: - Reading this attribute will provide the firmware - given instance (SMBIOS type 41 device type instance) of the - PCI device. The attribute will be created only if the firmware - has given an instance number to the PCI device. + Reading this attribute will provide the firmware given instance + number of the PCI device. Depending on the platform this can + be for example the SMBIOS type 41 device type instance or the + user-defined ID (UID) on s390. The attribute will be created + only if the firmware has given an instance number to the PCI + device and that number is guaranteed to uniquely identify the + device in the system. Users: Userspace applications interested in knowing the firmware assigned device type instance of the PCI |