This is defaulted off as it has potentially large memory costs for a modest
performance gain. Ideally we will improve DRM performance to the point where
this optimization is not worth the memory cost in any case, or find some
middle ground in caching only limited numbers of certain buffers. For now,
this provides a modest 4% improvement in openarena on GM965 and 10% in openarena
on GM945.
When the DRI doesn't parse the event buffer for a while, the X server
may overwrite data that the driver didn't get a chance to look at. The
reemitDrawableInfo callback requests that the X server reemit all info
for the specified drawable. To make use of this, the drive needs to know
the new tail pointer so it know where to start reading from.
This also fixes the problem where the X server does multiple resizes before
the DRI driver gets the events. The obsolete buffer attach events then
reference already destroyed buffer objects.
This opcode is likely a mistake from reverse engineering. MAD_2 isn't included
in AMD's documentation, and my testing reviles there is no problem using the
documented MAD opcode.
Instead of passing in a fixed struct, the loader now passes in a list
of __DRIextension structs, to advertise the functionality it can provide
to the driver. Each extension is individually versioned and can be
extended or phased out as the interface develops.
Right now the DRI2 screen constructor takes 3 different versions:
DRI, DDX and DRM. This is mostly useless, though:
DRI: The DRI driver doesn't actually care about the DRI protocol,
it only talks to the loader, which in turn speaks DRI protocol. Thus,
the DRI protocol version is of not interest to the DRI driver, but it
needs to know what functionality the loader provides. At this point
that's reflected in the __DRIinterfaceMethods struct and the
internal_version integer.
DDX: The DDX version number is essentially used to track extensions
to the SAREA. With DRI2 the SAREA consists of a number of versioned,
self-describing blocks, so the DDX version is no longer interesting.
DRM: We have the fd, lets just ask the kernel ourselves.
