pci device info access in linux from userspace

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I want to access the pci device tree information from user space programatically. Like the root complex and the devices connected to it. How can I do it please let me know.

Regards, Pradeep

4

There are 4 answers

0
Claudio On BEST ANSWER

libpci or pcilib (on which lspci is based) uses sysfs, procfs, and possibly other means to access PCI information. You can check pciutils package source code for further reference:

https://github.com/gittup/pciutils

https://github.com/gittup/pciutils/blob/gittup/lspci.c

2
0xDen On

From command line try to use lspci -tv command. But as far as I understand this command just parses /proc... If you need to do your task from program, you may have a look at lspci source code.

0
Paebbels On

You can access many information by browsing the sysfs. It's also possible to write to some files in sysfs to execute certain commands like a PCI bus re-enumeration ;)

For example listing all PCI devices can be done by:

paebbels@debian8:/sys/bus/pci/devices$ ll /sys/bus/pci/devices
insgesamt 0
drwxr-xr-x 2 root root 0 Dez 12 00:33 .
drwxr-xr-x 5 root root 0 Dez 12 00:33 ..
lrwxrwxrwx 1 root root 0 Dez 12 00:33 0000:00:00.0 -> ../../../devices/pci0000:00/0000:00:00.0
lrwxrwxrwx 1 root root 0 Dez 12 00:33 0000:00:01.0 -> ../../../devices/pci0000:00/0000:00:01.0
lrwxrwxrwx 1 root root 0 Dez 12 00:33 0000:00:07.0 -> ../../../devices/pci0000:00/0000:00:07.0
lrwxrwxrwx 1 root root 0 Dez 12 00:33 0000:00:07.1 -> ../../../devices/pci0000:00/0000:00:07.1
lrwxrwxrwx 1 root root 0 Dez 12 00:33 0000:00:07.3 -> ../../../devices/pci0000:00/0000:00:07.3
...
lrwxrwxrwx 1 root root 0 Dez 12 00:33 0000:00:18.2 -> ../../../devices/pci0000:00/0000:00:18.2
lrwxrwxrwx 1 root root 0 Dez 12 00:33 0000:00:18.3 -> ../../../devices/pci0000:00/0000:00:18.3
lrwxrwxrwx 1 root root 0 Dez 12 00:33 0000:00:18.4 -> ../../../devices/pci0000:00/0000:00:18.4
lrwxrwxrwx 1 root root 0 Dez 12 00:33 0000:00:18.5 -> ../../../devices/pci0000:00/0000:00:18.5
lrwxrwxrwx 1 root root 0 Dez 12 00:33 0000:00:18.6 -> ../../../devices/pci0000:00/0000:00:18.6
lrwxrwxrwx 1 root root 0 Dez 12 00:33 0000:00:18.7 -> ../../../devices/pci0000:00/0000:00:18.7
lrwxrwxrwx 1 root root 0 Dez 12 00:33 0000:02:00.0 -> ../../../devices/pci0000:00/0000:00:11.0/0000:02:00.0
lrwxrwxrwx 1 root root 0 Dez 12 00:33 0000:02:01.0 -> ../../../devices/pci0000:00/0000:00:11.0/0000:02:01.0
lrwxrwxrwx 1 root root 0 Dez 12 00:33 0000:02:02.0 -> ../../../devices/pci0000:00/0000:00:11.0/0000:02:02.0
lrwxrwxrwx 1 root root 0 Dez 12 00:33 0000:02:03.0 -> ../../../devices/pci0000:00/0000:00:11.0/0000:02:03.0
lrwxrwxrwx 1 root root 0 Dez 12 00:33 0000:03:00.0 -> ../../../devices/pci0000:00/0000:00:15.0/0000:03:00.0

Note: This is a Debian inside VMWare -> flat PCI hierachy.

Here is an example of device 0000:02:00.0:

paebbels@debian8:/sys/bus/pci/devices/0000:02:00.0$ ls -ahlL /sys/bus/pci/devices/0000\:02\:00.0
insgesamt 0
drwxr-xr-x 4 root root    0 Dez 12 00:37 .
drwxr-xr-x 8 root root    0 Dez 12 00:37 ..
-r--r--r-- 1 root root 4,0K Dez 12 00:37 acpi_index
-rw-r--r-- 1 root root 4,0K Dez 12 00:37 broken_parity_status
-r--r--r-- 1 root root 4,0K Dez 12 00:37 class
-rw-r--r-- 1 root root  256 Dez 12 00:37 config
-r--r--r-- 1 root root 4,0K Dez 12 00:37 consistent_dma_mask_bits
-rw-r--r-- 1 root root 4,0K Dez 12 00:37 d3cold_allowed
-r--r--r-- 1 root root 4,0K Dez 12 00:37 device
-r--r--r-- 1 root root 4,0K Dez 12 00:37 dma_mask_bits
drwxr-xr-x 2 root root    0 Dez  8 11:18 driver -> ../../../../bus/pci/drivers/uhci_hcd
-rw-r--r-- 1 root root 4,0K Dez 12 00:37 driver_override
-rw-r--r-- 1 root root 4,0K Dez 12 00:37 enabled
drwxr-xr-x 3 root root    0 Dez 12 00:37 firmware_node -> ../../../LNXSYSTM:00/LNXSYBUS:00/PNP0A03:00/device:05/device:06
-r--r--r-- 1 root root 4,0K Dez 12 00:37 irq
-r--r--r-- 1 root root 4,0K Dez 12 00:37 label
-r--r--r-- 1 root root 4,0K Dez 12 00:37 local_cpulist
-r--r--r-- 1 root root 4,0K Dez 12 00:37 local_cpus
-r--r--r-- 1 root root 4,0K Dez 12 00:37 modalias
-rw-r--r-- 1 root root 4,0K Dez 12 00:37 msi_bus
-r--r--r-- 1 root root 4,0K Dez 12 00:37 numa_node
-r--r--r-- 1 root root 4,0K Dez 12 00:37 pools
drwxr-xr-x 2 root root    0 Dez 12 00:37 power
--w--w---- 1 root root 4,0K Dez 12 00:37 remove
--w--w---- 1 root root 4,0K Dez 12 00:37 rescan
--w------- 1 root root 4,0K Dez 12 00:37 reset
-r--r--r-- 1 root root 4,0K Dez 12 00:37 resource
-rw------- 1 root root   32 Dez 12 00:37 resource4
drwxr-xr-x 5 root root    0 Dez 12 00:33 subsystem -> ../../../../bus/pci
-r--r--r-- 1 root root 4,0K Dez 12 00:37 subsystem_device
-r--r--r-- 1 root root 4,0K Dez 12 00:37 subsystem_vendor
-rw-r--r-- 1 root root 4,0K Dez 12 00:37 uevent
drwxr-xr-x 5 root root    0 Dez 12 00:37 usb4
-r--r--r-- 1 root root 4,0K Dez 12 00:37 vendor

You can see that device 0000:02:00.0 uses the driver 'uhci_hcd'.

Nice browsing :)

0
Nick Pershyn On

Superuser uses 'lspci' if pciutils is installed.

 # which lspci
/usr/sbin/lspci

If you are a regular user you might get something like this:

 $ lspci
-bash: lspci: command not found

You still can use it(from user space or program) if you specify absolute file path(the output of 'which' executed by root):

 $ /usr/sbin/lspci