I am trying to understand the console= parameter provided to the kernel and doing so I have modified /etc/default/grub
to set console up to be tty3 such as (the reason I have chosen tty3 as opposed to ttyS0 is that I don't have a serial port):
I am assuming by setting up console to be tty3 the kernel will only output messages to tty3 and no other tty. I have entered using Ctrl+Alt+F2 into tty2 and pressed the key Alt+SysRq+H. If I check dmesg
I can see the message there.
By doing that I can see the message of the kernel in the current tty2. By navigating to tty3 I do not see any messages.
Just for completeness, console is configured correctly to point to tty3:
~$ cat /sys/devices/virtual/tty/console/active
tty3
Furthermore to this, I have compiled a generic helloworld
module and performed insmod and rmmod on it. The output appears on the currently active tty and not the specified console (tty3).
I don't understand why this is happening. Could someone explain? Have I misunderstood the console parameter?
/dev/
. ThettyN
devices (where N>1) are allocated on demand from userspace, I think - and at that time there is no userspace. Anyway, I also like to see messages on a VT, but I do that with syslog (/etc/rsyslog.conf
since I use mostly Debian and derivatives). Also see the sysctl settingkernel.printk
for a way to regulate console noise.