about legal aspect of using GNU linux

[pratyush]

Hi all,
We are willing to use GNU Linux in our next project based of AT91RM9200 platform.But a vendor of Comercial RTOS told us that if we use it then we will have to release the source code of application.Please note that we are concerned about source code of application not that of kernel and devce driver.
i have gone through GPL documnet but it does not seem to be like that.
Can any clarify my doubts?

Regards
Pratyush

[ulf]

Unless you link your application with the Linux Kernel, you don't
have to release the source.
I think (but am not 100% sure) that you can use the available libraries.
If you use dynamically linked libraries you should be on the safe side.

[ulf]

Unless you link your application with the Linux Kernel, you don't
have to release the source.
I think (but am not 100% sure) that you can use the available libraries.
If you use dynamically linked libraries you should be on the safe side.

[Onitake]

that's not quite correct: the GPL explicitly states that any usage of GPL'd code makes the resulting software to be released under the GPL. that does not include linkage but it does include header files which are compiled in. on the other hand, most standard libraries either contain a special clause that permits compilation and linkage (like gcc-lib) or are released under LGPL which is less restrictive (like glibc).
there's also an exception with kernel modules: you are allowed to release kernel modules under your own license, but you have to mark these modules internally (insmod gives a nice warning about "tainting" your kernel when loading the module) so they can be distinguished from the bare GPL linux kernel.
in short, if you change something on existing GPL code, you have to release these changes. if you develop a device and write applications and kernel modules for it without stealing code from of GPL software, they remain your property alone.
i suggest googling around a little. there are a lot of resources on using linux in proprietary devices.

[bruce vicknair]

The way I read it , only commerically released software( for sale) had to be GPL.
If you give it away like I do; it is not required to include sources.

I write POSIX code in userland and LKM. If kernel changes are necessary i guess that would be GPL.

Does it really matter anyway? Do you think all of the Chinese multimedia players' source are posted somewhere?

[Onitake]

no, it's not only about commercial software.
all software that uses GPL has to be GPL (or GPL-compatible), no matter how it is released.
if you just do work in userland and don't include GPL'd libraries like ffmpeg, you can do anything you like. afaik though it is perfectly permissible to link with ffmpeg and state the ffmpeg license + copyright in your software eula.
correction: after all, it is not. see the following link: http://www.gnu.org/licenses/gpl-faq.html
only the lgpl allows linkage.

actually i think it does matter. have you heard of the xvid case? sigma design stole the xvid source code and released a video encoder/decoder containing that code as their own production (for free though). since they did a bad job obfuscating the binaries, someone found out about it and subsequently xvid.org stopped distribution of their codec. the issue has been settled now, but it shows that GPL infringers should be as careful as CS infringers.
here's more info: http://www.xvid.org/press/press-2002082 ... rce=240802
(or go to xvid.com and search for "sigma")

remember: linux does not force you to do something. it just leaves others the freedom to do the same as you.

[bruce vicknair]

Taken from http://www.gnu.org/licenses/gpl-faq.html

"Does the GPL require that source code of modified versions be posted to the public?
The GPL does not require you to release your modified version. You are free to make modifications and use them privately, without ever releasing them. This applies to organizations (including companies), too; an organization can make a modified version and use it internally without ever releasing it outside the organization.

But if you release the modified version to the public in some way, the GPL requires you to make the modified source code available to the program's users, under the GPL.

Thus, the GPL gives permission to release the modified program in certain ways, and not in other ways; but the decision of whether to release it is up to you. "

[jdupre]

no, it's not only about commercial software.
all software that uses GPL has to be GPL (or GPL-compatible), no matter how it is released.
if you just do work in userland and don't include GPL'd libraries like ffmpeg, you can do anything you like. afaik though it is perfectly permissible to link with ffmpeg and state the ffmpeg license + copyright in your software eula.
correction: after all, it is not. see the following link: http://www.gnu.org/licenses/gpl-faq.html
only the lgpl allows linkage.

What about the "standard" (POSIX?) C libraries?. The "version" of stdio provided by glibc is covered by the Lesser GPL. How can GNU/FSF apply a licence to a de facto standard? Is GNU's implementaion of the stdio library any different than Microsoft's ??? Aren't the POSIX standard C libraries in the public domain?

I find it difficult to believe that the use of the Gnu's glibc stdio library requires me to provide my source to anybody who requests it.

If so, is there an alternate set of standard C libraries in the public domain?

-jmd

[Onitake]

don't misunderstand the lgpl.
it's only about the effective implementation, i.e. the source code, not about the techniques, standards, etc. it implements.
anyone can implement his/her own version of POSIX if he/she likes to.
but if you choose to use lgpl software, you have to take certain things into account.
as the lgpl is much less restrictive than the gpl, you can do a lot more with it. you are allowed to incorporate its object into your own software, as in linking a static libc.a with your program.
if need to change things in the library itself and don't want to release those changes (exception: internal use in not-public projects is completely unrestricted), then you have to choose different software.
in this case, i recommend newlib (http://sourceware.org/newlib/) which basically has a BSD-style license. It also contains code from many manufacturers, whose specific licenses have to be looked into. They are similar to the main license though AFAIK.