Richard Smith [off-list ref] wrote:

Kendall Bennett wrote:

quoted

I would assume however a serial port console would be fine for embedded 
machines until the framebuffer driver could come up anyway.

This would be an incorrect assumption.  Speaking as a developer of
one said embedded system I must have video at boot and be able to
dump critical kernel messages to the screen. 

In the field, hooking up a serial cable to see why the unit
doesn't boot requires the dispatch of a tech who would have open
up the unit to get to the serial port.  This costs the end client
lots of $$.  They don't like that. 

By having video on boot the support person can tell the end user
to look at the screen and read back any messages and then make the
determination if a tech dispatch is needed. 

And its common practice to only have as many serial ports as the
system needs during runtime.  During development you can dual
purpose them but in the final system their may not be a serial
port free (or even installed) to get that console info from. 

Good, so my assumption was incorrect which I am happy about. Since it 
makes the work we did more useful ;-)

Anyway in your case do you need diagnostic messages just from the kernel 
or from the firmware as well? To get it in the firmware the video boot 
code would need to be ported there (U-Boot has a version of it already, 
but it is the only firmware I am aware of that supports this).

Regards,

---
Kendall Bennett
Chief Executive Officer
SciTech Software, Inc.
Phone: (530) 894 8400
http://www.scitechsoft.com

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