Re: [tboot-devel] Enhance serial support in tboot

[Ross P. <Ros...@ci...>]

Great. I will update the early serial logging to be similar to xen
including allowing you to specify the IO port and crystal frequency to
support external serial port cards and send a patch. I think I sent you
a patch earlier to enable early VGA but that was trivial - the VGA
support is already there, just not used so it will need a command line
way to turn it on. I would probably just use the xen command line format
unless anyone has a better idea.

 

Thanks

Ross

 

From: Cihula, Joseph [mailto:jos...@in...] 
Sent: Wednesday, November 12, 2008 4:27 AM
To: Ross Philipson; tbo...@li...
Subject: RE: Enhance serial support in tboot

 

I've been giving some thought to this and I think that it would be
valuable to have a command line parameter that allowed specifying how
logging is done:  VGA, memory, serial (and any combination of them or
lack of them).  The serial parameter would also need to support
specifying the various serial configs .

 

I've been holding off on this because I wanted to limit the amount of
command line options since the command line is not currently part of the
measurement of tboot, and thus there is a greater potential for
malicious manipulation of the code via command line.  E.g. if by adding
more command line options one of them introduces a buffer overflow then
there would be no way to determine if a given invocation of tboot was
done with such a malicious command line.

 

But I think that it is time to bite the bullet and add the command line
to the tboot measurement.  So with that support, making the command line
more complex will be less risky.  I'll take care of the command line
measurement changes, but I would welcome patches for the above logging
support.

 

Joe

P.S.  Back from vacation now so emails should be more timely.

 

From: Ross Philipson [mailto:Ros...@ci...] 
Sent: Monday, November 03, 2008 11:14 AM
To: tbo...@li...
Subject: [tboot-devel] Enhance serial support in tboot

 

I have recently been working on laptops that do not have serial ports so
I have been using an ExpressCard serial adapter. I had to make
modification to tboot to use a different IO port and clock frequency. I
have found that having serial debug output for tboot is incredibly
valuable during development.

 

The Xen console driver (on which the tboot early_printk is loosely based
as it seems) allows serial console configuration with command line
arguments (including setting the clock freq. now). I was thinking of
pulling this into tboot but I wanted to see if the community thought
this was something valuable to do - something that could be incorporated
in tboot?

 

Thanks

Ross

 

Ross Philipson

Senior Software Engineer

Citrix Systems, Inc

14 Crosby Drive

Bedford, MA 01730

781-301-7949

ros...@ci...