port-amd64/58367: prekern does not honor console device

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>Number:         58367
>Category:       port-amd64
>Synopsis:       prekern does not honor console device
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    port-amd64-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jun 25 08:20:00 +0000 2024
>Originator:     Harold Gutch
>Release:        netbsd-current
>Organization:
>Environment:
NetBSD  9.99.92 NetBSD 9.99.92 (GENERIC) #0: Tue Jun 25 08:25:24 CEST 2024  h@ubuntu:/home/h/netbsd/bugs/kaslr_test/out/sys/arch/amd64/compile/GENERIC amd64
>Description:
prekern prints its output only on VGA console.  If KASLR works, this is not a big deal, it only prints a few messages and then moves on, but if KASLR is broken this makes it annoying to debug over serial console.
>How-To-Repeat:
Take a machine with KASLR (e.g., 9.x), attach a serial console and set "consdev com0" in the boot loader.  Observe that none of the prekern output ends up on the serial console.
>Fix:
Don't use a serial console.