port-amd64/57523: [PATCH] efiboot/x86: Add serial console support via raw I/O port access

[rokuyama.rk%gmail.com@localhost]

>Number:         57523
>Category:       port-amd64
>Synopsis:       [PATCH] efiboot/x86: Add serial console support via raw I/O port access
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-amd64-maintainer
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Thu Jul 13 06:05:00 +0000 2023
>Originator:     Rin Okuyama
>Release:        10.99.3
>Organization:
Internet Initiative Japan Inc.
>Environment:
NetBSD netbsd 10.99.3 NetBSD 10.99.3 (AMD64_NET_MPSAFE) #1: Thu May 25 19:17:12 JST 2023  rin@latipes:/build/src/sys/arch/amd64/compile/AMD64_NET_MPSAFE amd64 x86_64
>Description:
Unfortunately, some (most?) UEFI implementations do not support
com ports by ``Serial I/O Protocol''.

``PNP0501-0'' and friends are not recognized also.

In this case, if user explicitly requires to switch to serial
console by ``consdev'' command, try to use raw I/O port access.

Yes, this is ugly, but what FreeBSD does, at least.
>How-To-Repeat:
Boot amd64/i386 machines with com(4) ports on UEFI mode, and
try ``consdev'' command. If you are lucky enough, serial
devices appear. But it fails in most cases, unfortunately.
>Fix:
https://github.com/rokuyama/netbsd-src/commit/47bf5414985451c577b54bcd5130680f1f6c7a35.diff