Re: licensing question?

Date: Tue Jun 21 2005 - 12:26:37 PDT

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    On Tue, Jun 21, 2005 at 10:39:12AM -0400, Richard Hu wrote:
    > To Whom It May Concern:
    > I have a question about the licensing involved in using the Berkeley
    > Labs Checkpoint Restart package (so hopefully you will bear with me if
    > this question becomes convoluted).
    > Libcr is covered by LGPL but from reading your paper "The Design and
    > Implementation of Berkeley Lab's Linux Checkpoint/Restart", it seems
    > that in order to checkpoint a program (even when you checkpoint it by
    > linking against libcr - not using cr_run) the checkpoint needs to
    > utilize vmadump.  However, vmadump is protected by GPL so would that
    > automatically cause libcr to be GPL instead of LGPL or is there
    > something else that mitigates that?
    Our code is a mixture of LGPL and GPL.  The parts that are in the kernel
    (i.e. our cr_module kernel module) are GPL.  This is the part that
    interacts with vmadump, so there's no licensing problem, since they're
    both GPL (not that there would necessarily have been a problem, anyway:
    the Linux kernel license does not require all modules to be GPL, and a
    module can use another module without having the same license).
    > Also, does libcr utilize cr_module at all?  If not, what is the
    > purpose of cr_module and does it affect the licensing for libcr in any
    > way?
    libcr does use cr_module.  But since there is a system call interface
    between them (libcr is user-level library, which uses system calls to
    interact with the kernel module), they do not need to have the same
    license.  This is why we use LGPL for the library.  This is exactly
    analogous to the way that the standard Linux C library (glibc) is LGPL,
    but uses system calls to the GPL kernel to accomplish much of its work.
    Again, no licensing problem here.
    > Essentially I'm trying to checkpoint a proprietary program and
    > wondering what the limitations on licensing are so I can determine
    > whether to utilize BLCR.  Any insight or help you can give will be
    > greatly appreciated.
    You are free to checkpoint ANY program, no matter how proprietary, with
    BLCR.  The 'cr_checkpoint' and 'cr_restart' programs can be invoked on
    any program without licensing issues.  The only licensing issues to
    worry about are if you are mixing the actual source code for these
    programs with your own source code.
    So you have no worries as near as I can tell, from what you've told me.
    Jason Duell             Future Technologies Group
    <jcduell_at_lbl_dot_gov>       Computational Research Division
    Tel: +1-510-495-2354    Lawrence Berkeley National Laboratory

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