install/47719: NetBSD install image: post-install: cannot reboot into existing GRUB / missing PPPoE

[renekuligowski%alice-dsl.net@localhost]

>Number:         47719
>Category:       install
>Synopsis:       NetBSD install image: post-install: cannot reboot into 
>existing GRUB / missing PPPoE
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    install-manager
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Fri Apr 05 20:25:00 +0000 2013
>Originator:     Renè Kuligowski
>Release:        6.0.1
>Organization:
>Environment:
not of concern; it is a general problem I encountered on three completely 
different machines/architectures.
>Description:
error #1: After base installation, I need PPPoE to open an internet connection 
in order to access any internet server.  NetBSD does NOT offer PPPoE 
configuration on the install image, so I'm stuck with the minimum system (and 
thus thinking to simply erase it and use the currently wasted space 
purposefully).

error #2: After installing NetBSD in parallel to debian GNU/Linux and telling 
sysinst not to install an MBR or a boot loader, I cannot re-boot into GRUB ?? 
neither the copy in the MNR nor the copy in the Linux partition's header.  I 
needed to run a debian rescue system USB image to re-install GRUB into the MBR.


>How-To-Repeat:
see the description.
>Fix:
fix to #1: impossible without pppoe packages on the installer image.

fix to #2: use a Linux rescue image; boot into existing Linux partition; 
re-install GRUB to MBR; insert the following into grub.cfg:

menuitem "NetBSD 6.0.1" --class netbsd --class bsd --class os {
  set root=(hdX,msdosY)
  chainloader +1
}

?where X and Y correspond to disk and partition of NetBSD install; finally, 
reboot machine.