On Thu, Feb 06, 2014 at 04:44:20PM +0100, Hannes Reinecke wrote: > On 02/06/2014 04:29 PM, Greg Kroah-Hartman wrote: > > On Thu, Feb 06, 2014 at 03:27:43PM +0100, Hannes Reinecke wrote: > >> The 'active' sysfs attribute should refer to the currently > >> active tty devices the console is running on, not the currently > >> active console. > > > > That's not what Documentation/ABI/sysfs-tty says: > > Shows the list of currently configured > > > > console devices, like 'tty1 ttyS0'. > > > > The last entry in the file is the active > > > > device connected to /dev/console. > > > > The file supports poll() to detect virtual > > > > console switches. > > > The problem is indeed with 'console devices'. There is no such > thing; you only have tty devices where the console is running on. > > >> The console structure doesn't refer to any device in sysfs, > >> only the tty the console is running on has. > > > > That sentance doesn't make sense. > > > >> So we need to print out the tty names in 'active', not > >> the console names. > > > > But that doesn't match the documentation. > > > > What exactly are you trying to "fix" here? What is the problem that the > > current file has that is broken? And as you are changing what this file > > means, what will break if the information in the file changes? > > > systemd is using the 'active' sysfs attribute to figure out on which > _tty_ device to start a getty on. > As soon as the console name and the tty name are different > you have no means of figuring out which _device_ to open. > AFAICS the console 'device' (ie the current entry in 'active') > doesn't have _any_ equivalent in sysfs; it just so happens that for > most console drivers the tty driver name is identical. > But this is not a requirement, and fails for drivers which have a > different device for the console and the tty. > > EG on S/390 the 3270 tty has the devices > > /dev/3270/tty1 > > but the console driver announces the name 'tty3270'. > So as per current rules the 'active' attribute contains > > tty32700 > > which correct as per documentation, but doesn't have _any_ > equivalent in sysfs. > > Martin has the grubby details here. > > But of course, the documentation should be updated to match the new > behavior.
Ok, care to send an updated version, that fixes the Documentation as well? If Kay agrees that this is the correct solution, I'll be glad to take it. thanks, greg k-h _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
