Comment 5 for bug 1879290

I think the answer here is to stop passing "console=ttyS0". This is something that is typically only done for debugging.

dmesg shows a 14 second delay between the "console [tty1] enabled" and "console [ttyS0] enabled" messages. I suspect that because console=ttyS0 is passed the kernel is going to dump all the messages accumulated in dmesg so far to the serial port when it is registered as a console device. Because this is a slow device this consumes significant time, and it happens in an initcall so it blocks boot progress. Then boot from that point on is slowed down by printing messages out on the serial port every time something is printed to the kernel log.