Re: [RFC 2/5] gcc: xtensa: make configuration dynamic

[Max Filippov <jcmvbkbc@gmail.com>]

On Fri, May 26, 2017 at 7:44 AM, Ian Lance Taylor <iant@google.com> wrote:
> On Thu, May 25, 2017 at 1:31 PM, Max Filippov <jcmvbkbc@gmail.com> wrote:
>> On Thu, May 25, 2017 at 11:24 AM, augustine.sterling@gmail.com
>> <augustine.sterling@gmail.com> wrote:
>>
>>> Please note that by using a plugin mechanism, there are licensing
>>> issues that come into play, that are different from the usual
>>> licensing issues. I would be absolutely sure that you all are OK with
>>> how the runtime exception applies to this new situation.
>>
>> All code used for building the configuration shared object is either GPL
>> (part of binutils) or MIT (xtensa configuration overlay), so it should be ok?
>
> You are in effect introducing a new kind of plugin mechanism.  I won't
> comment on whether it should use the existing plugin mechanism or not,
> but it's important to stress that the GCC Runtime Library Exception
> (https://www.gnu.org/licenses/gcc-exception-3.1.en.html) has rules
> that apply here.  In effect, if you want to distribute the binary
> produced by GCC, all the plugins that you use must be available under
> a GPL-compatible license.  The people to whom you distribute the
> binary produced by GCC must be able to themselves build the plugin
> used to create the binary.  The plugin may not have any proprietary
> source code.

Thanks, that's how I understood that. I've added a note to the plugin
README: https://github.com/jcmvbkbc/xtensa-dynconfig/blob/master/README

> One way that the GCC plugin mechanism makes that clear is by requiring
> the plugin to define a symbol named, literally,
> "plugin_is_GPL_compatible".  While there is no enforcement mechanism
> as such, this ensures that the person creating the plugin acknowledges
> that at the very least the plugin is supposed to be under a GPL
> compatible license.  I think that if you are going to introduce a new
> plugin mechanism, you should adopt the same approach.

Sure I can add such requirement to this mechanism and implement that
check.

-- 
Thanks.
-- Max