On Thu, Jan 11, 2018 at 06:43:54PM +0100, Greg KH wrote: > 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: >> >>> 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, None of the boards in question are hot-pluggable, so that last one doesn't matter. > and all sorts of other problems. This isn't the 1990's anymore :) What do you recommend as a means for providing configuration information to a serial driver for a PCI multi-port serial board? > What exactly are you trying to "configure" that can't be done today with > the existing tty api? The big issue is which minor number (and therefore device name) goes with which DB9 connector. A general solution that allowed arbitrary mapping would be ideal (our Windows drivers allow this), but it would be acceptable to have a simpler solution where the starting minor number for each board could be configured. > If your PCI devices change, use a differnet naming scheme, like one > based on a MAC address. That's what I do (assign user-defined interface names to cards with specific MAC addresses), but most distros seem to assume that the PCI address mapping is stable. >> 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 :) It must be stable enough for common cases, since distros like Ubuntu seem to depend on it. > Have you looked at the /dev/serial/ links? That's about the best we can > get for "deterministic" names for serial devices, sorry. The customer I'm dealing with at the moment runs RedHat 7.4 (kernel 3.10.0) and doesn't have /dev/serial. On other systems it looks like /dev/serial only gets created for USB serial devices -- it doesn't seem to get created for PCI serial devices. Should it exist for PCI serial ports? [That may be an oversight in the udev rules provided by the distros. Regardless of the reason, it doesn't look like I can plan on using /dev/serial.] > Not much you can do about broken hardware and crazy BIOSes :) True, but I get paid to try... :) -- Grant -- 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
