Re: kern/53311: boot netbsd -d panics

[Valery Ushakov <uwe%stderr.spb.ru@localhost>]

The following reply was made to PR kern/53311; it has been noted by GNATS.

From: Valery Ushakov <uwe%stderr.spb.ru@localhost>
To: Andreas Gustafsson <gson%gson.org@localhost>
Cc: gnats-bugs%NetBSD.org@localhost
Subject: Re: kern/53311: boot netbsd -d panics
Date: Sun, 27 May 2018 16:05:28 +0300

 On Sun, May 27, 2018 at 15:41:46 +0300, Andreas Gustafsson wrote:
 
 > Valery Ushakov wrote:
 > > >  By bisection, I found that the problem started with the following
 > > >  commit:
 > > >  
 > > >    2018.03.16.04.48.19 ozaki-r src/sys/arch/x86/x86/db_memrw.c 1.6
 > > >  
 > > >  I suggest reverting it (and its pullup).
 > > 
 > > This is from March 2018.  The boot -d + bt triple fault that I
 > > reported above is on i386 with 8.99.12 from late January 2018.  So
 > > that's probably not the whole story.
 > 
 > To me it looks like "boot netbsd -d panics" (immediately) and
 > "entering bt after boot -d causes triple fault" are two separate
 > problems
 
 The timeline I see is 
 
 - entering "bt" after "boot -d" causes triple fault (virtualbox guru)
   with late January kernel on i386
 
 - "bt" is now executed automatically when entering ddb, committed on
   February 17
 
   http://mail-index.netbsd.org/source-changes/2018/02/17/msg092275.html
 
 - "boot -d" causes panic/reset on real hardware
 
 I may be infering wrong conclusions.
 
 Also, the latter report is for amd64, while the triple fault I see is
 on i386.  I found another VM that is amd64 and has kerel from Feb 15,
 and it doesn't show that problem - bt after boot -d works ok.
 
 Did you bisect/test on amd64 or i386?  If that was only on amd64, does
 the kernel before the commit you identified as problematic also work
 on i386?
 
 -uwe