waffle: Change WAFFLE_CONTEXT_PROFILE behavior for GL

This patch changes the behavior of WAFFLE_CONTEXT_PROFILE when the
requested api is WAFFLE_CONTEXT_OPENGL.

At commit a40dec1~1 (Nov 12), the behavior was:
    - For GL < 3.2, require that the profile be WAFFLE_NONE, core,
      or compat.
    - For GL >= 3.2, require that the profile be core or compat.
This is the behavior released in waffle-1.1.

However, the waffle_config manpage documented requirements for
WAFFLE_CONTEXT_PROFILE that differed from the implementation. The
documented requirements imitated the EGL_KHR_create_context and
GLX_ARB_create_context_profile specs.  Commit a40dec1 (Nov 12) changed the
behavior to match the manpage:
    - For GL < 3.2, completely ignore the profile value.
    - For GL >= 3.2, require that the profile be core or compat.
This behavior had looser requirements than a40dec1~1 because the profile's
value was not validated for GL < 3.2. No waffle release contains a40dec1.

The GLX working group, though, can't decide on the exact behavior of
profile bit.  A later GLX extension, GLX_EXT_create_context_es_profile, is
built on top of but breaks backwards compatibility with
GLX_ARB_create_context_profile. According to
GLX_EXT_create_context_es_profile, the profile *is* signficant for all
versions of GL when its value is GLX_CONTEXT_PROFILE_ES_BIT_EXT.

Rather than attempt to predict what the GLX working group will decide
next regarding the profile bit, Waffle should be as restrictive as
possible in its interpretation of WAFFLE_CONTEXT_PROFILE. Being
restrictive decreases the possibility that Waffle will accept something
that a later GLX extension will reject, a situation that would likely
result in modifying the public interface or internal ugliness.

This patch changes the behavior to be more sightly more restrictive than
a40dec1~1:
    - For GL < 3.2, require that the profile be WAFFLE_NONE.
    - For GL >= 3.2, require that the profile be core or compat.
It will be straightforward to later loosen these requirements if necessary
in response to a new GLX or EGL extension.

This patch also updates the waffle_config manpage and wcore_config_attrs
unittests accordingly.

Even though the current requirements are more restrictive than those
released in waffle-1.1,  I don't expect this to change to break any
clients. The only clients I'm aware of are Piglit, which is not affected
by this change, and some experimental unreleased apps.

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>

1 files changed, 11 insertions, 5 deletions

diff --git a/man/waffle_config.3.xml b/man/waffle_config.3.xml
index a0f20e5..9f196a6 100644
--- a/man/waffle_config.3.xml
+++ b/man/waffle_config.3.xml
@@ -320,15 +320,21 @@ struct waffle_config;
           </para>
 
           <para>
-            If the requested API is <constant>WAFFLE_CONTEXT_OPENGL</constant>,
+            If the requested API is <constant>WAFFLE_CONTEXT_OPENGL</constant>
 
-            then default value is <constant>WAFFLE_CONTEXT_CORE_PROFILE</constant>.
+            and the requested version is less than 3.2,
+
+            then the default and only accepted value is <constant>WAFFLE_NONE</constant>.
+          </para>
+
+          <para>
+            If the requested API is <constant>WAFFLE_CONTEXT_OPENGL</constant>
 
-            If the requested context version is less than 3.2,
+            and the requested version is at least 3.2,
 
-            then the value of <constant>WAFFLE_CONTEXT_PROFILE</constant> is ignored.
+            then default value is <constant>WAFFLE_CONTEXT_CORE_PROFILE</constant>.
 
-            If the requested context version is at least 3.2, then the set of accepted values is
+            The set of accepted values is
 
             <constant>WAFFLE_CONTEXT_PROFILE_CORE</constant> and
             <constant>WAFFLE_CONTEXT_PROFILE_COMPATIBILITY</constant>.