mesa: allow buffers to be mapped multiple times

OpenGL allows a buffer to be mapped only once, but we also map buffers
internally, e.g. in the software primitive restart fallback, for PBOs,
vbo_get_minmax_index, etc. This has always been a problem, but it will
be a bigger problem with persistent buffer mappings, which will prevent
all Mesa functions from mapping buffers for internal purposes.

This adds a driver interface to core Mesa which supports multiple buffer
mappings and allows 2 mappings: one for the GL user and one for Mesa.

Note that Gallium supports an unlimited number of buffer and texture
mappings, so it's not really an issue for Gallium.

v2: fix unmapping in xm_dd.c, remove the GL errors there
v3: fix the intel driver (by Fredrik)

Reviewed-by: Fredrik Höglund <[email protected]>

1 files changed, 3 insertions, 2 deletions

diff --git a/src/mesa/main/api_validate.c b/src/mesa/main/api_validate.c
index ce007e26598..f3fd1a47569 100644
--- a/src/mesa/main/api_validate.c
+++ b/src/mesa/main/api_validate.c
@@ -69,7 +69,8 @@ _mesa_max_buffer_index(struct gl_context *ctx, GLuint count, GLenum type,
    if (_mesa_is_bufferobj(elementBuf)) {
       /* elements are in a user-defined buffer object.  need to map it */
       map = ctx->Driver.MapBufferRange(ctx, 0, elementBuf->Size,
-				       GL_MAP_READ_BIT, elementBuf);
+				       GL_MAP_READ_BIT, elementBuf,
+                                       MAP_INTERNAL);
       /* Actual address is the sum of pointers */
       indices = (const GLvoid *) ADD_POINTERS(map, (const GLubyte *) indices);
    }
@@ -92,7 +93,7 @@ _mesa_max_buffer_index(struct gl_context *ctx, GLuint count, GLenum type,
    }
 
    if (map) {
-      ctx->Driver.UnmapBuffer(ctx, elementBuf);
+      ctx->Driver.UnmapBuffer(ctx, elementBuf, MAP_INTERNAL);
    }
 
    return max;