On Mon, Jan 26, 2015 at 02:40:58PM -0500, Jon Masters wrote: > Hi Folks, > > TLDR: I need a back reference from a console struct to its device.
I know I'm going to regret answering this vague question, but, what _exactly_ do you mean by "its device"? > I can't see an easy way to do this right now without adding one? >From within the kernel or from userspace? If in the kernel, what part of the kernel are you doing this from? If in userspace, what is wrong with /sys/class/tty/console? > I've a quick question. I have prototype code that parses an ACPI table > known as the SPCR (Serial Port Console Redirection - exists on both x86 > and ARM systems). It finds the correct serial device (but it's not a > Linux specific DT-style solution so there's no "console=" parameter > embedded in it or something) to use for the preferred console (I have > effectively the device object connected with the acpi_handle of the > underlying serial device, which I map on by walking the ACPI namespace > down from the root until I find the _ADR of the specified SPCR address). > > One of the problems that I have is that I want to make the decision > about whether a console should be automatically configured once we get > to register_console, because that's where the existing logic is, and > it's one path I can be sure everyone is going to call (serial drivers > have a number of different APIs that they use during registration). > > Once I'm in register_console, I have only the console struct to play > with. I can get from that to the tty_driver (by walking the tty driver > list and finding the back reference), but that still doesn't give me > what I want. I can add a reference to the underlying device in one of > these structs, but I would like to have additional opinions before I go > and make something hackish folks will balk at later. So, am I missing > something obvious? I hope I am because this seems slightly weird. I really don't understand what you are wanting to do here. Who wants to "automatically configure" a console? > P.S. I would love it if I could (for debug purposes only) just walk down > from the root of the kernel device hierarchy until I found a device that > had a resource matching the one I am looking for (you can do exactly > this in the ACPI namespace using exported methods), but the only code > that can do that today is unexported core core used during shutdown to > shutdown all devices recursively. Just a sidenote. Sorry, you don't know what "type" of devices you are walking through, so bad things can happen if you guess wrong. greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
