On Tue, Oct 1, 2013 at 1:51 PM, Warren Young <warren at etr-usa.com> wrote: > On 9/30/2013 21:34, Barry Brimer wrote: >>> I'm using 115200, 8N1, VT102. I can echo m > /proc/sysctl-trigger, >>> and dmesg shows that the sysrq was received when initiated via the >>> procfs interface. But not over serial, and that's what I need. >> >> I could be wrong .. but you may need to edit your grub config to convince >> your system that the serial terminal is a/the console .. > > That's only part of it. The topic has a whole HOWTO dedicated to it: > > http://www.tldp.org/HOWTO/Remote-Serial-Console-HOWTO/ I'm familiar with that howto, and have set up serial console many times. The only thing new here is the usb serial adapter. I am not particularly interested in having serial access during the early stages of booting, which is what you configure in grub. I want it to come up post-boot, preferably after insertion of a specific USB serial dongle. And I cannot break (if you pardon the pun) sysrq (or any other) capability at the physical ps2/vga console. To be clear, serial console WORKS currently for me with usb serial adapters. What DOESN'T work is SysRq via that serial console. My understanding is that the 'console=' kernel argument controls pre-init serial console, so that you can see the output of various kernel modules as they load. Once an agetty starts, it takes over the serial console functionality from the kernel. Because I'm only interested in adding this serial console post-boot, I don't think I need to configure console=. I'd like to know why this is wrong if it is. -- Billy Crook • Network and Security Administrator • RiskAnalytics, LLC