Confusing Usage-Guide in LICENSES/exceptions/Linux-syscall-note

From: Orivej Desh
Date: Fri Feb 21 2020 - 22:37:29 EST

For the reference, here is the Linux syscall note:

NOTE! This copyright does *not* cover user programs that use kernel
services by normal system calls - this is merely considered normal use
of the kernel, and does *not* fall under the heading of "derived work".

When Linux-syscall-note was split from the COPYING file [1] [2], it
added a Usage-Guide section that says that "This exception" marks
"user space API (uapi) header files so they can be included into non
GPL compliant user space application code". However, the License-Text
extracted from the COPYING does not say anything about including
headers; instead it says that programs that make system calls to the
kernel are not considered derived from the kernel.

I think that Linus shares the view expressed by Stallman [3]:

Someone recently made the claim that including a header file
always makes a derivative work.

That's not the FSF's view. Our view is that just using structure
definitions, typedefs, enumeration constants, macros with simple
bodies, etc., is NOT enough to make a derivative work. It would
take a substantial amount of code (coming from inline functions
or macros with substantial bodies) to do that.

and wrote the syscall note as something to be added on top of this
view, while Thomas Gleixner took the note as a relaxation of GPL that
allows the use of the headers in non-GPL programs when he wrote the
Usage-Guide and Documentation/process/license-rules.rst that says:

The User-space API (UAPI) header files, which describe the
interface of user-space programs to the kernel are a special
case. According to the note in the kernel COPYING file, the
syscall interface is a clear boundary, which does not extend the
GPL requirements to any software which uses it to communicate
with the kernel. Because the UAPI headers must be includable into
any source files which create an executable running on the Linux
kernel, the exception must be documented by a special license

I think that the lawyers should review whether the syscall note grants
anything not already granted by GPL-2.0. If it unambiguously does not
than the note could be deleted, overwise the following mistakes should
be corrected:

1. Since the note declares user programs to not be considered derived
from the running kernel, it applies to the kernel as a whole. It
does not make sense to restrict Linux-syscall-note to UAPI headers
only (in their SPDX-License-Identifier) and not to apply it to the
whole kernel. "WITH Linux-syscall-note" should be deleted from all
sources; the link to the note from the root COPYING is enough.

2. Linux-syscall-note should be cleared from these parts of the old
COPYING unrelated to the note:

Also note that the GPL below is copyrighted by the Free Software
Foundation, but the instance of code that it refers to (the Linux
kernel) is copyrighted by me and others who actually wrote it.

Also note that the only valid version of the GPL as far as the kernel
is concerned is _this_ particular version of the license (ie v2, not
v2.2 or v3.x or whatever), unless explicitly otherwise stated.

Linus Torvalds

Note that there is no GPL text below.

3. Linux-syscall-note Usage-Guide could be deleted (does a three line
note need a guide?), or it may say something like this:

This exception allows non-GPL programs to run on Linux.

4. Documentation/process/license-rules.rst should be updated
accordingly. Something like the Stallman explanation of derived
works would be useful.

5. SPDX license list maintainers should be notified to update [5]. Its
current Note about the exception is unclear and mistaken:

This note is used with the Linux kernel to clarify how user space
API files should be treated.

The people seem easily confused by the Usage-Guide: they believe that
the syscall exception does what it does not (allowing uapi includes in
user programs), and do not understand what it does (allowing making
system calls). Please correct it!



This is my second attempt to reach @vger, as my message from seems to
have been dropped.

Please CC me in response.