On Thu, Jan 11, 2018 at 11:36:51AM -0600, Grant Edwards wrote: > On Thu, Jan 11, 2018 at 08:26:52AM +0100, Greg KH wrote: > > On Wed, Jan 10, 2018 at 09:17:23PM +0000, Grant Edwards wrote: > > > >> If a user needs to provide configuration information specific to a > >> particular PCI board, how does one have the user identify the > >> board? > > > > It's a hard thing to do :( > > > >> When my driver's probe() function is called, it appears that > >> pdev->slot is null, so that's not useful. > > > > Yes, not all BIOSes support that. > > > >> Should I use pci_name(pdev) as the identifier for the user to > >> specify when configuring a particular board? > > > > You can, but how are you "configuring a particular board"? > > The thought was that there would be a module parameter that contained > sets of "board ID" and config values. What could be used for the > "board ID" is the question. Through a bit of trial and error, the > user can determine which pci_name (e.g. 0000:07:00.0) belongs to which > board. If those names are "stable", then the user could then create a > module parameter with the desired configuration value(s) for each > pci_name. Ick, no, don't use module parameters, they do not scale, users never know how to use them, they don't work for devices you add after you load the module, and all sorts of other problems. This isn't the 1990's anymore :) What exactly are you trying to "configure" that can't be done today with the existing tty api? > > > Is pci_name(pdev) associated with a phisical slot guaranteed to be > > > unchaged after a reboot? After other PCI cards are added/removed? > > > > It can randomly change every boot, the PCI addressing scheme is not > > deterministic, sorry. > > But doesn't the new "predictable" network interface naming scheme > assume that it is deterministic and name the device based on its PCI > address? If your PCI devices change, use a differnet naming scheme, like one based on a MAC address. > $ ifconfig | grep '^en' > enp1s5 Link encap:Ethernet HWaddr 00:13:8f:ff:20:ba > > $ lspci | grep -i Ethernet > 01:05.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8100/8101L/8139 PCI Fast Ethernet Adapter (rev 10) > > $ cat /etc/network/interfaces > [...] > auto enp1s5 > iface enp1s5 inet static > address 192.168.14.253 > netmask 255.255.0.0 > gateway 192.168.0.253 > dns-nameservers 8.8.8.8 8.8.4.4 > > If the PCI addressing scheme isn't predictable after reboot, then > won't the network device name change and the network configuration get > broken? Yes it will. Happens all the time :) > At least with network cards, there's a MAC address you can use to > differentiate one card from another if you need to. With all of the > serial cards I've seen, there isn't: if you install multiple serial > cards of the same model, they're completely identical from the > driver's POV. Perhaps they should have had serial numbers that the > driver could read, but there's no way the additional cost can be > justified when multiple-card installations are uncommon. Have you looked at the /dev/serial/ links? That's about the best we can get for "deterministic" names for serial devices, sorry. Not much you can do about broken hardware and crazy BIOSes :) greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
