Hi Greg, > > 1* /proc/bus/pci/devices doesn't appear to contain PCI domain > > information. I guess it only lists the devices on domain 0000, and > > would miss devices on multi-domain machines? > > Yes, it doesn't contain domain info on x86 boxes. Not sure about bigger > ones like ia64 or ppc64. I just checked on two ia64 boxes, one with domains and one without, and the info doesn't appear to be in /proc/bus/pci/devices (same column count, none of which matched the domains). The difference is in the names of the directories below /proc/bus/pci. On the multi-domain ia64 machine: dr-xr-xr-x 2 root root 0 2006-09-02 22:08 0001:00 dr-xr-xr-x 2 root root 0 2006-09-02 22:08 0002:00 dr-xr-xr-x 2 root root 0 2006-09-02 22:08 0003:00 dr-xr-xr-x 2 root root 0 2006-09-02 22:08 0004:00 dr-xr-xr-x 2 root root 0 2006-09-02 22:08 0005:00 dr-xr-xr-x 2 root root 0 2006-09-02 22:08 0006:00 dr-xr-xr-x 2 root root 0 2006-09-02 22:08 0011:00 dr-xr-xr-x 2 root root 0 2006-09-02 22:08 0012:00 dr-xr-xr-x 2 root root 0 2006-09-02 22:08 0013:00 dr-xr-xr-x 2 root root 0 2006-09-02 22:08 0013:01 dr-xr-xr-x 2 root root 0 2006-09-02 22:08 0014:00 dr-xr-xr-x 2 root root 0 2006-09-02 22:08 0014:01 dr-xr-xr-x 2 root root 0 2006-09-02 22:08 0015:00 dr-xr-xr-x 2 root root 0 2006-09-02 22:08 0015:01 dr-xr-xr-x 2 root root 0 2006-09-02 22:08 0016:00 -r--r--r-- 1 root root 0 2006-09-02 22:08 devices On another machine: dr-xr-xr-x 2 root root 0 2006-09-02 22:09 00 dr-xr-xr-x 2 root root 0 2006-09-02 12:31 01 dr-xr-xr-x 2 root root 0 2006-09-02 22:09 02 -r--r--r-- 1 root root 0 2006-09-02 22:09 devices So on the multi-domain machine, the domain is prepended to the bus number. This is where lspci appears to be taking the information when told to use /proc. I found that lspci was using /sys/bus/pci/devices by default on Linux 2.6. It can be forced back to using /proc/bus/pci, with more or less success depending on the system. > > 2* Since which kernel version does /sys/bus/pci/devices look like the > > way it is right now? Did the device IDs always include the PCI domain? > > If it's stable since 2.6.0, I could use it in sensors-detect. > > /sys/bus/pci/devices has always been there since 2.6.0. I don't know > for sure about the format of the pci bus ids, but I think they have been > the same since that time too. Good. I checked on 2.6.5 (Suse flavor) and it's indeed the same. And I think supporting from 2.6.5 is good enough, nobody sane would use a 2.6 kernel older than that these days. > > 3* Will /sys/bus/pci/devices go away eventually? > > No, that is the proper way to easily enumerate all PCI devices in the > system. X is also switching over to use this, so it can not go away any > time in the next couple of years, unless something really wrong is found > with it (and something new would have to be created for it, which I > don't see happening...) Damn. I thought your answer was a bit strange, until I read my question again and noticed I had messed up ;) Let me try again: 3B* Will /proc/bus/pci go away eventually? Of course, I did not expect /sys/bus/pci/devices to go away by the next 7 years... > Hope this helps, Well, now I get to decide what I want to do. I need the PCI class and this doesn't appear to be easy to get using /proc/bus/pci (you need to walk through subdirectories, and extract the 3 class bytes from each binary file.) This seems much easier to get it from /sys/bus/pci/devices (single directory to get the list, then just one text file to read to get the class for each device.) For now my code is a ugly hack reading the device list from /proc/bus/pci/devices, then for each device the class from /sys/bus/pci/devices if available. That was the shortest path from the current code to what I wanted to do, and was good enough for testing, but I'd be ashamed to commit it as is. The only advantage is the compatibility with 2.4 kernels. Thanks, -- Jean Delvare
