From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Kroah-Hartman Subject: Re: Device to write to all (serial) consoles Date: Fri, 2 Aug 2019 18:02:43 +0200 Message-ID: <20190802160243.GA15484@kroah.com> References: <32c2d26f-ec4a-b9a6-b42c-07b27f99ea28@molgen.mpg.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <32c2d26f-ec4a-b9a6-b42c-07b27f99ea28@molgen.mpg.de> Sender: linux-kernel-owner@vger.kernel.org To: Paul Menzel Cc: linux-serial@vger.kernel.org, Linux Kernel Mailing List , Donald Buczek List-Id: linux-serial@vger.kernel.org On Fri, Aug 02, 2019 at 03:23:08PM +0200, Paul Menzel wrote: > Dear Linux folks, > > > On a lot of devices, like servers, you have more than one serial console, > and you do not always know, how they are numbered. Therefore, we start a > console on ttyS0 and ttyS1. > > In user space, we also would like to write to both consoles to not worry > about the numbering. Writing to `/dev/console` only write to the active > console. So the same data to multiple console devices with just one userspace call? Why? > $ more /proc/consoles # I think > tty0 -WU (EC p ) 4:1 > ttyS0 -W- (E p a) 4:65 > ttyS1 -W- (E p a) 4:65 > > Does a device exist, or can a device be configured so you can write to > all (serial) consoles from user space? With one syscall, not that I know of, sorry. greg k-h