Re: low level I/O (GPIB, USBTMC, VXI11)

[Richard Stallman]

    > It is my understanding you can link with whatever you want for your 
personal usage.
    > However, DISTRIBUTING a binary that links with NI VISA definitely 
violates the GPL.
    > That is why I don't distribute binaries, only source code.

The user, on his own initiative, is free to link GPL-covered code with
nonfree code and use that privately.  However, to modify a GPL-covered
program so that it is meant to link to some non-free code, and
distribute that, is not a private action.  It is a way of combining
the program with nonfree code.  That violates the GPL.

    I've never been clear if this is really ok, but it seems to be a
    common interpretation. It seems to be, for example, how nvidia gets
    around Linux's copyleft and the nvidia blob.

nVidia's nonfree driver violates the GPL, but the Linux developers
choose not to object.  We can't force them to enforce their license.

As for the firmware blobs, there is an argument that firmware programs
are separate programs merely packaged together with Linux, and thus
not violations of the GPL.  However, the issue is moot since the
copyright holders of Linux choose not to enforce the GPL anyway.

    Richard, can you comment on this? A number of Octave users create oct
    files to talk to non-free libraries for external hardware. An oct file
    is basically a C++ program that uses Octave's headers and links to
    Octave. It is my understanding that these oct files are also linking
    to non-free libraries. I am uncomfortable that people do this and
    distribute the results. What do you think?

That could be a GPL violation.  We need to look at the specific
details.

-- 
Dr Richard Stallman
President, Free Software Foundation
51 Franklin St
Boston MA 02110
USA
www.fsf.org  www.gnu.org
Skype: No way! That's nonfree (freedom-denying) software.
  Use Ekiga or an ordinary phone call