RE: KGDB, serial ports, and MP

["Paul Koning" <Paul_Koning%Dell.com@localhost>]

The comment was made when I proposed that fix is that it will NOT handle
the MP case because splserial() doesn't affect other CPUs.  And one of
the commenters pointed me to places to look for how to do the MP part.

I haven't done that yet; it's on my to-do list.  I need to find an MP
host to test it on...

        paul

> -----Original Message-----
> From: tech-kern-owner%NetBSD.org@localhost 
> [mailto:tech-kern-owner%NetBSD.org@localhost]
On
> Behalf Of Greg Troxel
> Sent: Wednesday, May 12, 2010 6:40 PM
> To: tech-kern%netbsd.org@localhost
> Subject: KGDB, serial ports, and MP
> 
> 
> I've run into the bug described at:
> 
>   http://mail-index.netbsd.org/netbsd-bugs/2010/03/17/msg016596.html
> 
> and the proposed fix (splserial) seems to work.  This is on an amd64
> VM;
> we'll try a physical (multi-cpu) machine as well.
> 
> Reading the various messages, I get the impression that KGDB on MP
> systems will behave a bit oddly; I don't understand if splserial on
one
> CPU will keep all CPUs from interrupting and trying to read.  Is
anyone
> working on a better fix, perhaps even as spiffy as letting gdb switch
> among CPUs?
> 
> I am guessing that for now one should just boot with a single CPU to
> use
> kgdb.  Does that sound like the right advice?
> 
>     Greg