port-amd64/53502: EFI booting of amd64 8.0 boot CD fails to detect all memory

[scole_mail%gmx.com@localhost]

>Number:         53502
>Category:       port-amd64
>Synopsis:       EFI booting of amd64 8.0 boot CD fails to detect all memory
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    port-amd64-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Aug 06 06:50:00 +0000 2018
>Originator:     scole
>Release:        8.0
>Organization:
none
>Environment:
NetBSD localhost 8.0 NetBSD 8.0 (GENERIC) #0: Tue Jul 17 14:59:51 UTC 2018  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC amd64
>Description:
When booting using EFI mode, the amd64 8.0 CD kernel doesn't detect all memory available:

NetBSD 8.0 (GENERIC) #0: Tue Jul 17 14:59:51 UTC 2018
        mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC
total memory = 3289 MB
avail memory = 3169 MB
...

When booting the CD in BIOS mode, all the memory is detected:

NetBSD 8.0 (GENERIC) #0: Tue Jul 17 14:59:51 UTC 2018
        mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC
total memory = 8125 MB
avail memory = 7866 MB
...

I won't be able to attempt an install on this machine, since it is not mine, so I don't know if the same problem exists once an install has been done.

I'll attach the dmesg's shortly.  But another difference is whether drm or genfb is used.
>How-To-Repeat:
boot amd64 8.0 CD in EFI mode
>Fix: