This is a simple script that compares the make variables set by two
different configs stubs. The purpose is to highlight differences so
that any unnecessary duplication or divergence can be removed.
For example, on Linux x86:
$ ./bin/confdiff.sh linux linux-x86
The output isn't very clean, but it should highlight that the only
difference is that the x86 target uses x86 assembler sources.
The script uses bash, mktemp, make, sed and diff. It is probably not
very portable and might only work on GNU make.
Mesa currently disables -fPIC for DRI on x86, but most Linux distros are
re-enabling -fPIC for all DRI arches. Let's just do that here since
that's normally what's wanted for shared libraries. Some justification:
http://bugs.gentoo.org/show_bug.cgi?id=110840#c9
On the other hand, position-independent code is only necessary when
building shared libraries, so disable it for the static cases.
* Fix crash at context creation in most drivers supporting vblank.
* Don't pass vblank sequence or flags to functions that get passed the drawable
private already.
* Attempt to initialize vblank related drawable private fields just once
per drawable. May need more work in some drivers.
Consolidate support for synchronizing to and retrieving vblank counters. Also
fix the core vblank code to return monotonic MSC counters, which are required
by some GLX extensions. Adding support for multiple pipes to a low level
driver is fairly easy, the Intel 965 driver provides simple example code (see
intel_buffers.c:intelWindowMoved()).
The new code bumps the media stream counter extension version to 2 and adds a
new getDrawableMSC callback. This callback takes a drawablePrivate pointer,
which is used to calculate the MSC value seen by clients based on the actual
vblank counter(s) returned from the kernel. The new drawable private fields
are as follows:
- vblSeq - used for tracking vblank counts for buffer swapping
- vblFlags - flags (e.g. current pipe), updated by low level driver
- msc_base - MSC counter from the last time the current pipe changed
- vblank_base - kernel DRM vblank counter from the last time the pipe changed
Using the above variables, the core vblank code (in vblank.c) can calculate a
monotonic MSC value. The low level DRI drivers are responsible for updating
the current pipe (by setting VBLANK_FLAG_SECONDARY for example in vblFlags)
along with msc_base and vblank_base whenever the pipe associated with a given
drawable changes (again, see intelWindowMoved for an example of this).
Drivers should fill in the GetDrawableMSC DriverAPIRec field to point to
driDrawableGetMSC32 and add code for pipe switching as outlined above to fully
support the new scheme.
