Subject: Re: Stallman vs Wind River on the GPL
From: Ian Lance Taylor <ian@airs.com>
Date: 22 Feb 2001 12:43:16 -0800

"Michael A. Olson" <mao@sleepycat.com> writes:

> There's an intersting article at
> 
> 	http://icd.pennnet.com/Articles/Article_Display.cfm?ARTICLE_ID=92350
> 
> on the practical effect of using Linux in embedded systems.

RTEMS (http://www.rtems.com/) is an example of an GPL'ed RTOS.  They
make it clear that the GPL only applies to changes to RTEMS proper,
not to application code.

I seem to recall that it is considered to be acceptable to distribute
device drivers for Linux as binary modules without source code.  I
don't know for sure whether that is true.  But if it is, that model
would work just as well for embedded Linux.

> All of the embedded RTOS vendors are either worried about
> Linux or have adopted it.

I've done a bit of embedded systems programming, and I never
considered using something as heavyweight as Linux.  There are plenty
of alternatives, including free ones like eCos
(http://sources.redhat.com/ecos/) and RTEMS (http://www.rtems.com/).
Linux is just fine if you are building an server appliance, which is
basically a server system without a monitor or keyboard.  It is hardly
appropriate for a hand-held pager.

I also recall seeing a survey that about 50% of embedded systems
developers roll their own RTOS anyhow.

> Schacker, from Wind River, raises a valid point:  Companies exist
> today who make money from licensing systems, including proprietary
> device drivers for special-purpose hardware, in the embedded market.

Those companies exist in the desktop market too.  I don't really see
that there is any significant difference in the embedded market.  So I
think it's just the repitition of the same old thing in a slightly new
context.

Ian