linux-kernel - ALT+CTRL+F2 - Switch Terminal

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Message-ID: <CAMaKedC_cprruUZ+1S_KVsoe_ZRk6AB6pui_w=BnsnER0Y0uiA@mail.gmail.com>
Date:   Thu, 9 Aug 2018 15:04:43 +1000
From:   Mohit Gupta <mohit@...oris.com.au>
To:     linux-kernel@...r.kernel.org
Subject: ALT+CTRL+F2 - Switch Terminal - agetty process

I am trying to understand how agetty process is called when
ALT+CTRL+F2/ALT+CTRL+F3/.... keys are pressed in CentOS or in any
other linux distro.

What I know so far
- systemd runs agetty.service with next tty[N] number
- agetty then run login process and then other process continues.

What I want to know
---------------------------
When ALT+CTRL+F2 keys are pressed what happens in kernel?

Looking at keyboard.c seems k_cons is called which calls set_console.

static void k_cons(struct vc_data *vc, unsigned char value, char up_flag)
{
   if (up_flag)
    return;

    set_console(value);
}

I am not sure how set_console triggers agetty with tty2/tty3/tty4 as
one of it's parameter.

Any information will be helpful.

Regards
Mohit