git: DragonFly_RELEASE_6_4 kernel - Fix early console probe when serial port does not exist

[Matthew Dillon]

commit 4fc43b13fa80f1af217a6c5223945d5c1f5fb03a
Author: Matthew Dillon <dillon at apollo.backplane.com>
Date:   Sat Jan 7 18:02:05 2023 -0800

    kernel - Fix early console probe when serial port does not exist
    
    * Newer machines may ship without any legacy serial ports at all,
      but our default sio0.flags (in the kernel config) are set to 0x10
      to enable console operation if syscons isn't available.
    
      If the serial port does not actually exist, this will panic or
      livelock the kernel in early boot.
    
    * Fix in two ways.  First, force sioN.disabled to TRUE if the sio
      device probe fails.  If the serial console probe is still reached,
      the serial console probe will also ensure that he serial port is
      able to drain before assigning it.
    
    * Fixes Ryzen 7000 series headless booting.  You can also workaround
      the issue by setting sio0.flags=0 in /boot/loader.conf if you do
      not have a fixed kernel.

Summary of changes:
 sys/dev/serial/sio/sio.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/4fc43b13fa80f1af217a6c5223945d5c1f5fb03a


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