Re: port-xen/40675: Xen 3.3: guest serial console not functional

["Christoph Egger" <Christoph_Egger%gmx.de@localhost>]

The following reply was made to PR port-xen/40675; it has been noted by GNATS.

From: "Christoph Egger" <Christoph_Egger%gmx.de@localhost>
To: Juergen Hannken-Illjes <hannken%eis.cs.tu-bs.de@localhost>, 
gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: port-xen/40675: Xen 3.3: guest serial console not functional
Date: Fri, 20 Feb 2009 17:01:01 +0100

 > On Fri, Feb 20, 2009 at 04:38:10PM +0100, Christoph Egger wrote:
 > > 
 > > > On Fri, Feb 20, 2009 at 02:56:51PM +0100, Christoph Egger wrote:
 > > > > 
 > > > > Nope, that doesn't fix it.
 > > > 
 > > > Did you try it out?
 > > 
 > > Yes. Sorry, I was too fast. I thought that doesn't fit with
 > > unix98 vs. BSD ptys.
 > > 
 > > I tested it on Linux, too. It works there, too.
 > > I can only send patches upstream which don't break Linux.
 > 
 > So my patch broke Linux?
 
 Actually it unbroke Linux. With your patch it works, no matter
 if you have unix98 ptys or BSD pty. W/o your patch and even
 w/o my patch, only unix98 ptys worked.
 My patch causes some troubles to unix98 ptys
 with certain glibc / linux kernel versions.
 
 > > > I had the problem described in this PR
 > > > on an amd64, running NetBSD-5.0_RC2 with xentools33 (2008Q4)
 > > > and it disappears with my patch.  I printed the terminal
 > > > attributes after openpty() and they were garbage on the
 > > > first console, valid on the second etc.
 > > 
 > > When openpty() returns garbage, isn't it broken then?
 > 
 > Openpty() gets garbage in (uninitialized attributes MODIFIED by
 > cfmakeraw()).
 > It sets the slave to the attributes requested.
 
 ah...
  
 > > > This just hides the bug.  We create a pty pair with random
 > > > attributes, close the slave so these attributes disappear
 > > > and hope the slave will be reopened and initialized.
 > > 
 > > And this happens on second console then ?
 > 
 > The initialization will come from xenconsole
 > (init_term(spty, ...)). This looks racey ...
 
 It is racey. There's a comment saying that at the very bottom
 of console/client/main.c.
 
 
 -- 
 Greetings,
 
 Christoph