mesa pixman xkeyboard-config git update 28 sep 2011

4 files changed, 188 insertions, 57 deletions

diff --git a/mesalib/src/mesa/main/enable.c b/mesalib/src/mesa/main/enable.c
index 23b6a9480..689dc8a99 100644
--- a/mesalib/src/mesa/main/enable.c
+++ b/mesalib/src/mesa/main/enable.c
@@ -304,7 +304,10 @@ _mesa_set_enable(struct gl_context *ctx, GLenum cap, GLboolean state)
       case GL_CLIP_DISTANCE6:
       case GL_CLIP_DISTANCE7:
          {
-            const GLuint p = cap - GL_CLIP_PLANE0;
+            const GLuint p = cap - GL_CLIP_DISTANCE0;
+
+            if (p >= ctx->Const.MaxClipPlanes)
+               goto invalid_enum_error;
 
             if ((ctx->Transform.ClipPlanesEnabled & (1 << p))
                 == ((GLuint) state << p))
@@ -1084,13 +1087,21 @@ _mesa_IsEnabled( GLenum cap )
 	 return ctx->Eval.AutoNormal;
       case GL_BLEND:
          return ctx->Color.BlendEnabled & 1;  /* return state for buffer[0] */
-      case GL_CLIP_PLANE0:
-      case GL_CLIP_PLANE1:
-      case GL_CLIP_PLANE2:
-      case GL_CLIP_PLANE3:
-      case GL_CLIP_PLANE4:
-      case GL_CLIP_PLANE5:
-	 return (ctx->Transform.ClipPlanesEnabled >> (cap - GL_CLIP_PLANE0)) & 1;
+      case GL_CLIP_DISTANCE0:
+      case GL_CLIP_DISTANCE1:
+      case GL_CLIP_DISTANCE2:
+      case GL_CLIP_DISTANCE3:
+      case GL_CLIP_DISTANCE4:
+      case GL_CLIP_DISTANCE5:
+      case GL_CLIP_DISTANCE6:
+      case GL_CLIP_DISTANCE7: {
+         const GLuint p = cap - GL_CLIP_DISTANCE0;
+
+         if (p >= ctx->Const.MaxClipPlanes)
+            goto invalid_enum_error;
+
+	 return (ctx->Transform.ClipPlanesEnabled >> p) & 1;
+      }
       case GL_COLOR_MATERIAL:
 	 return ctx->Light.ColorMaterialEnabled;
       case GL_CULL_FACE:
diff --git a/mesalib/src/mesa/main/get.c b/mesalib/src/mesa/main/get.c
index 99ce567cc..cddea8ea2 100644
--- a/mesalib/src/mesa/main/get.c
+++ b/mesalib/src/mesa/main/get.c
@@ -102,6 +102,8 @@ enum value_type {
    TYPE_BIT_3,
    TYPE_BIT_4,
    TYPE_BIT_5,
+   TYPE_BIT_6,
+   TYPE_BIT_7,
    TYPE_FLOAT,
    TYPE_FLOAT_2,
    TYPE_FLOAT_3,
@@ -134,6 +136,7 @@ enum value_extra {
    EXTRA_NEW_FRAG_CLAMP,
    EXTRA_VALID_DRAW_BUFFER,
    EXTRA_VALID_TEXTURE_UNIT,
+   EXTRA_VALID_CLIP_DISTANCE,
    EXTRA_FLUSH_CURRENT,
 };
 
@@ -189,6 +192,8 @@ union value {
 #define CONTEXT_BIT3(field) CONTEXT_FIELD(field, TYPE_BIT_3)
 #define CONTEXT_BIT4(field) CONTEXT_FIELD(field, TYPE_BIT_4)
 #define CONTEXT_BIT5(field) CONTEXT_FIELD(field, TYPE_BIT_5)
+#define CONTEXT_BIT6(field) CONTEXT_FIELD(field, TYPE_BIT_6)
+#define CONTEXT_BIT7(field) CONTEXT_FIELD(field, TYPE_BIT_7)
 #define CONTEXT_FLOAT(field) CONTEXT_FIELD(field, TYPE_FLOAT)
 #define CONTEXT_FLOAT2(field) CONTEXT_FIELD(field, TYPE_FLOAT_2)
 #define CONTEXT_FLOAT3(field) CONTEXT_FIELD(field, TYPE_FLOAT_3)
@@ -239,6 +244,11 @@ static const int extra_valid_texture_unit[] = {
    EXTRA_END
 };
 
+static const int extra_valid_clip_distance[] = {
+   EXTRA_VALID_CLIP_DISTANCE,
+   EXTRA_END
+};
+
 static const int extra_flush_current_valid_texture_unit[] = {
    EXTRA_FLUSH_CURRENT,
    EXTRA_VALID_TEXTURE_UNIT,
@@ -515,12 +525,14 @@ static const struct value_desc values[] = {
    { GL_ALPHA_TEST_FUNC, CONTEXT_ENUM(Color.AlphaFunc), NO_EXTRA },
    { GL_ALPHA_TEST_REF, LOC_CUSTOM, TYPE_FLOATN, 0, extra_new_frag_clamp },
    { GL_BLEND_DST, CONTEXT_ENUM(Color.Blend[0].DstRGB), NO_EXTRA },
-   { GL_CLIP_PLANE0, CONTEXT_BIT0(Transform.ClipPlanesEnabled), NO_EXTRA },
-   { GL_CLIP_PLANE1, CONTEXT_BIT1(Transform.ClipPlanesEnabled), NO_EXTRA },
-   { GL_CLIP_PLANE2, CONTEXT_BIT2(Transform.ClipPlanesEnabled), NO_EXTRA },
-   { GL_CLIP_PLANE3, CONTEXT_BIT3(Transform.ClipPlanesEnabled), NO_EXTRA },
-   { GL_CLIP_PLANE4, CONTEXT_BIT4(Transform.ClipPlanesEnabled), NO_EXTRA },
-   { GL_CLIP_PLANE5, CONTEXT_BIT5(Transform.ClipPlanesEnabled), NO_EXTRA },
+   { GL_CLIP_DISTANCE0, CONTEXT_BIT0(Transform.ClipPlanesEnabled), extra_valid_clip_distance },
+   { GL_CLIP_DISTANCE1, CONTEXT_BIT1(Transform.ClipPlanesEnabled), extra_valid_clip_distance },
+   { GL_CLIP_DISTANCE2, CONTEXT_BIT2(Transform.ClipPlanesEnabled), extra_valid_clip_distance },
+   { GL_CLIP_DISTANCE3, CONTEXT_BIT3(Transform.ClipPlanesEnabled), extra_valid_clip_distance },
+   { GL_CLIP_DISTANCE4, CONTEXT_BIT4(Transform.ClipPlanesEnabled), extra_valid_clip_distance },
+   { GL_CLIP_DISTANCE5, CONTEXT_BIT5(Transform.ClipPlanesEnabled), extra_valid_clip_distance },
+   { GL_CLIP_DISTANCE6, CONTEXT_BIT6(Transform.ClipPlanesEnabled), extra_valid_clip_distance },
+   { GL_CLIP_DISTANCE7, CONTEXT_BIT7(Transform.ClipPlanesEnabled), extra_valid_clip_distance },
    { GL_COLOR_MATERIAL, CONTEXT_BOOL(Light.ColorMaterialEnabled), NO_EXTRA },
    { GL_CURRENT_COLOR,
      CONTEXT_FIELD(Current.Attrib[VERT_ATTRIB_COLOR0][0], TYPE_FLOATN_4),
@@ -1798,6 +1810,13 @@ check_extra(struct gl_context *ctx, const char *func, const struct value_desc *d
 	    return GL_FALSE;
 	 }
 	 break;
+      case EXTRA_VALID_CLIP_DISTANCE:
+	 if (d->pname - GL_CLIP_DISTANCE0 >= ctx->Const.MaxClipPlanes) {
+	    _mesa_error(ctx, GL_INVALID_ENUM, "%s(clip distance %u)",
+			func, d->pname - GL_CLIP_DISTANCE0);
+	    return GL_FALSE;
+	 }
+	 break;
       case EXTRA_END:
 	 break;
       default: /* *e is a offset into the extension struct */
@@ -1986,6 +2005,8 @@ _mesa_GetBooleanv(GLenum pname, GLboolean *params)
    case TYPE_BIT_3:
    case TYPE_BIT_4:
    case TYPE_BIT_5:
+   case TYPE_BIT_6:
+   case TYPE_BIT_7:
       shift = d->type - TYPE_BIT_0;
       params[0] = (*(GLbitfield *) p >> shift) & 1;
       break;
@@ -2073,6 +2094,8 @@ _mesa_GetFloatv(GLenum pname, GLfloat *params)
    case TYPE_BIT_3:
    case TYPE_BIT_4:
    case TYPE_BIT_5:
+   case TYPE_BIT_6:
+   case TYPE_BIT_7:
       shift = d->type - TYPE_BIT_0;
       params[0] = BOOLEAN_TO_FLOAT((*(GLbitfield *) p >> shift) & 1);
       break;
@@ -2166,6 +2189,8 @@ _mesa_GetIntegerv(GLenum pname, GLint *params)
    case TYPE_BIT_3:
    case TYPE_BIT_4:
    case TYPE_BIT_5:
+   case TYPE_BIT_6:
+   case TYPE_BIT_7:
       shift = d->type - TYPE_BIT_0;
       params[0] = (*(GLbitfield *) p >> shift) & 1;
       break;
@@ -2260,6 +2285,8 @@ _mesa_GetInteger64v(GLenum pname, GLint64 *params)
    case TYPE_BIT_3:
    case TYPE_BIT_4:
    case TYPE_BIT_5:
+   case TYPE_BIT_6:
+   case TYPE_BIT_7:
       shift = d->type - TYPE_BIT_0;
       params[0] = (*(GLbitfield *) p >> shift) & 1;
       break;
@@ -2348,6 +2375,8 @@ _mesa_GetDoublev(GLenum pname, GLdouble *params)
    case TYPE_BIT_3:
    case TYPE_BIT_4:
    case TYPE_BIT_5:
+   case TYPE_BIT_6:
+   case TYPE_BIT_7:
       shift = d->type - TYPE_BIT_0;
       params[0] = (*(GLbitfield *) p >> shift) & 1;
       break;
@@ -2618,6 +2647,8 @@ _mesa_GetFixedv(GLenum pname, GLfixed *params)
    case TYPE_BIT_3:
    case TYPE_BIT_4:
    case TYPE_BIT_5:
+   case TYPE_BIT_6:
+   case TYPE_BIT_7:
       shift = d->type - TYPE_BIT_0;
       params[0] = BOOLEAN_TO_FIXED((*(GLbitfield *) p >> shift) & 1);
       break;
diff --git a/mesalib/src/mesa/main/texgetimage.c b/mesalib/src/mesa/main/texgetimage.c
index 2830dda86..d2f25b9f8 100644
--- a/mesalib/src/mesa/main/texgetimage.c
+++ b/mesalib/src/mesa/main/texgetimage.c
@@ -71,14 +71,13 @@ type_with_negative_values(GLenum type)
 static void
 get_tex_depth(struct gl_context *ctx, GLuint dimensions,
               GLenum format, GLenum type, GLvoid *pixels,
-              const struct gl_texture_image *texImage)
+              struct gl_texture_image *texImage)
 {
    const GLint width = texImage->Width;
    const GLint height = texImage->Height;
    const GLint depth = texImage->Depth;
    GLint img, row;
    GLfloat *depthRow = (GLfloat *) malloc(width * sizeof(GLfloat));
-   const GLint texelSize = _mesa_get_format_bytes(texImage->TexFormat);
 
    if (!depthRow) {
       _mesa_error(ctx, GL_OUT_OF_MEMORY, "glGetTexImage");
@@ -86,18 +85,24 @@ get_tex_depth(struct gl_context *ctx, GLuint dimensions,
    }
 
    for (img = 0; img < depth; img++) {
+      GLubyte *srcMap;
+      GLint srcRowStride;
+
+      /* map src texture buffer */
+      ctx->Driver.MapTextureImage(ctx, texImage, img,
+                                  0, 0, width, height, GL_MAP_READ_BIT,
+                                  &srcMap, &srcRowStride);
+
       for (row = 0; row < height; row++) {
          void *dest = _mesa_image_address(dimensions, &ctx->Pack, pixels,
                                           width, height, format, type,
                                           img, row, 0);
-         const GLubyte *src = (GLubyte *) texImage->Data +
-            (texImage->ImageOffsets[img] +
-             texImage->RowStride * row) * texelSize;
-
+         const GLubyte *src = srcMap + row * srcRowStride;
          _mesa_unpack_float_z_row(texImage->TexFormat, width, src, depthRow);
-
          _mesa_pack_depth_span(ctx, width, dest, type, depthRow, &ctx->Pack);
       }
+
+      ctx->Driver.UnmapTextureImage(ctx, texImage, img);
    }
 
    free(depthRow);
@@ -110,27 +115,35 @@ get_tex_depth(struct gl_context *ctx, GLuint dimensions,
 static void
 get_tex_depth_stencil(struct gl_context *ctx, GLuint dimensions,
                       GLenum format, GLenum type, GLvoid *pixels,
-                      const struct gl_texture_image *texImage)
+                      struct gl_texture_image *texImage)
 {
    const GLint width = texImage->Width;
    const GLint height = texImage->Height;
    const GLint depth = texImage->Depth;
-   const GLint rowstride = texImage->RowStride;
-   const GLuint *src = (const GLuint *) texImage->Data;
    GLint img, row;
 
    for (img = 0; img < depth; img++) {
+      GLubyte *srcMap;
+      GLint rowstride;
+
+      /* map src texture buffer */
+      ctx->Driver.MapTextureImage(ctx, texImage, img,
+                                  0, 0, width, height, GL_MAP_READ_BIT,
+                                  &srcMap, &rowstride);
+
       for (row = 0; row < height; row++) {
+	 const GLubyte *src = srcMap + row * rowstride;
          void *dest = _mesa_image_address(dimensions, &ctx->Pack, pixels,
                                           width, height, format, type,
                                           img, row, 0);
+         /* XXX Z24_S8 vs. S8_Z24??? */
          memcpy(dest, src, width * sizeof(GLuint));
          if (ctx->Pack.SwapBytes) {
             _mesa_swap4((GLuint *) dest, width);
          }
-
-         src += rowstride;
       }
+
+      ctx->Driver.UnmapTextureImage(ctx, texImage, img);
    }
 }
 
@@ -141,17 +154,24 @@ get_tex_depth_stencil(struct gl_context *ctx, GLuint dimensions,
 static void
 get_tex_ycbcr(struct gl_context *ctx, GLuint dimensions,
               GLenum format, GLenum type, GLvoid *pixels,
-              const struct gl_texture_image *texImage)
+              struct gl_texture_image *texImage)
 {
    const GLint width = texImage->Width;
    const GLint height = texImage->Height;
    const GLint depth = texImage->Depth;
-   const GLint rowstride = texImage->RowStride;
-   const GLushort *src = (const GLushort *) texImage->Data;
    GLint img, row;
 
    for (img = 0; img < depth; img++) {
+      GLubyte *srcMap;
+      GLint rowstride;
+
+      /* map src texture buffer */
+      ctx->Driver.MapTextureImage(ctx, texImage, img,
+                                  0, 0, width, height, GL_MAP_READ_BIT,
+                                  &srcMap, &rowstride);
+
       for (row = 0; row < height; row++) {
+	 const GLubyte *src = srcMap + row * rowstride;
          void *dest = _mesa_image_address(dimensions, &ctx->Pack, pixels,
                                           width, height, format, type,
                                           img, row, 0);
@@ -168,9 +188,9 @@ get_tex_ycbcr(struct gl_context *ctx, GLuint dimensions,
          else if (ctx->Pack.SwapBytes) {
             _mesa_swap2((GLushort *) dest, width);
          }
-
-         src += rowstride;
       }
+
+      ctx->Driver.UnmapTextureImage(ctx, texImage, img);
    }
 }
 
@@ -221,8 +241,32 @@ get_tex_rgba(struct gl_context *ctx, GLuint dimensions,
          return;
       }
 
-      _mesa_decompress_image(texFormat, texImage->Width, texImage->Height,
-                             texImage->Data, texImage->RowStride, tempImage);
+      /* Decompress the texture image - results in 'tempImage' */
+      {
+         GLubyte *srcMap;
+         GLint srcRowStride;
+         GLuint bytes, bw, bh;
+
+         bytes = _mesa_get_format_bytes(texImage->TexFormat);
+         _mesa_get_format_block_size(texImage->TexFormat, &bw, &bh);
+
+         ctx->Driver.MapTextureImage(ctx, texImage, 0,
+                                     0, 0, width, height,
+                                     GL_MAP_READ_BIT,
+                                     &srcMap, &srcRowStride);
+
+         /* XXX This line is a bit of a hack to work around the
+          * mismatch of compressed row strides as returned by
+          * MapTextureImage() vs. what the texture decompression code
+          * uses.  This will be fixed in the future.
+          */
+         srcRowStride = srcRowStride * bh / bytes;
+
+         _mesa_decompress_image(texFormat, width, height,
+                                srcMap, srcRowStride, tempImage);
+
+         ctx->Driver.UnmapTextureImage(ctx, texImage, 0);
+      }
 
       if (baseFormat == GL_LUMINANCE ||
           baseFormat == GL_LUMINANCE_ALPHA) {
@@ -250,7 +294,6 @@ get_tex_rgba(struct gl_context *ctx, GLuint dimensions,
    }
    else {
       /* No decompression needed */
-      const GLint texelSize = _mesa_get_format_bytes(texFormat);
       GLuint img, row;
       GLfloat (*rgba)[4];
 
@@ -261,13 +304,19 @@ get_tex_rgba(struct gl_context *ctx, GLuint dimensions,
       }
 
       for (img = 0; img < depth; img++) {
+	 GLubyte *srcMap;
+	 GLint rowstride;
+
+         /* map src texture buffer */
+         ctx->Driver.MapTextureImage(ctx, texImage, img,
+                                     0, 0, width, height, GL_MAP_READ_BIT,
+                                     &srcMap, &rowstride);
+
          for (row = 0; row < height; row++) {
+	    const GLubyte *src = srcMap + row * rowstride;
             void *dest = _mesa_image_address(dimensions, &ctx->Pack, pixels,
                                              width, height, format, type,
                                              img, row, 0);
-            const GLubyte *src = (const GLubyte *) texImage->Data +
-               (texImage->ImageOffsets[img] +
-                texImage->RowStride * row) * texelSize;
 
             _mesa_unpack_rgba_row(texFormat, width, src, rgba);
 
@@ -307,6 +356,9 @@ get_tex_rgba(struct gl_context *ctx, GLuint dimensions,
                                        format, type, dest,
                                        &ctx->Pack, transferOps);
          }
+
+         /* Unmap the src texture buffer */
+         ctx->Driver.UnmapTextureImage(ctx, texImage, img);
       }
 
       free(rgba);
@@ -319,15 +371,13 @@ get_tex_rgba(struct gl_context *ctx, GLuint dimensions,
  * \return GL_TRUE if done, GL_FALSE otherwise
  */
 static GLboolean
-get_tex_memcpy(struct gl_context *ctx, GLenum format, GLenum type, GLvoid *pixels,
-               const struct gl_texture_object *texObj,
-               const struct gl_texture_image *texImage)
+get_tex_memcpy(struct gl_context *ctx, GLenum format, GLenum type,
+               GLvoid *pixels,
+               struct gl_texture_object *texObj,
+               struct gl_texture_image *texImage)
 {
    GLboolean memCopy = GL_FALSE;
 
-   /* Texture image should have been mapped already */
-   assert(texImage->Data);
-
    /*
     * Check if the src/dst formats are compatible.
     * Also note that GL's pixel transfer ops don't apply to glGetTexImage()
@@ -386,20 +436,28 @@ get_tex_memcpy(struct gl_context *ctx, GLenum format, GLenum type, GLvoid *pixel
                                texImage->Height, format, type, 0, 0);
       const GLint dstRowStride =
          _mesa_image_row_stride(&ctx->Pack, texImage->Width, format, type);
-      const GLubyte *src = texImage->Data;
-      const GLint srcRowStride = texImage->RowStride * bpp;
-      GLuint row;
+      GLubyte *src;
+      GLint srcRowStride;
+
+      /* map src texture buffer */
+      ctx->Driver.MapTextureImage(ctx, texImage, 0,
+                                  0, 0, texImage->Width, texImage->Height,
+                                  GL_MAP_READ_BIT, &src, &srcRowStride);
 
       if (bytesPerRow == dstRowStride && bytesPerRow == srcRowStride) {
          memcpy(dst, src, bytesPerRow * texImage->Height);
       }
       else {
+         GLuint row;
          for (row = 0; row < texImage->Height; row++) {
             memcpy(dst, src, bytesPerRow);
             dst += dstRowStride;
             src += srcRowStride;
          }
       }
+
+      /* unmap src texture buffer */
+      ctx->Driver.UnmapTextureImage(ctx, texImage, 0);
    }
 
    return memCopy;
@@ -409,7 +467,8 @@ get_tex_memcpy(struct gl_context *ctx, GLenum format, GLenum type, GLvoid *pixel
 /**
  * This is the software fallback for Driver.GetTexImage().
  * All error checking will have been done before this routine is called.
- * The texture image must be mapped.
+ * We'll call ctx->Driver.MapTextureImage() to access the data, then
+ * unmap with ctx->Driver.UnmapTextureImage().
  */
 void
 _mesa_get_teximage(struct gl_context *ctx, GLenum target, GLint level,
@@ -419,9 +478,6 @@ _mesa_get_teximage(struct gl_context *ctx, GLenum target, GLint level,
 {
    GLuint dimensions;
 
-   /* If we get here, the texture image should be mapped */
-   assert(texImage->Data);
-
    switch (target) {
    case GL_TEXTURE_1D:
       dimensions = 1;
@@ -433,6 +489,7 @@ _mesa_get_teximage(struct gl_context *ctx, GLenum target, GLint level,
       dimensions = 2;
    }
 
+   /* map dest buffer, if PBO */
    if (_mesa_is_bufferobj(ctx->Pack.BufferObj)) {
       /* Packing texture image into a PBO.
        * Map the (potentially) VRAM-based buffer into our process space so
@@ -487,11 +544,11 @@ _mesa_get_compressed_teximage(struct gl_context *ctx, GLenum target, GLint level
                               struct gl_texture_object *texObj,
                               struct gl_texture_image *texImage)
 {
-   const GLuint row_stride = _mesa_format_row_stride(texImage->TexFormat,
-                                                     texImage->Width);
-   const GLuint row_stride_stored = _mesa_format_row_stride(texImage->TexFormat,
-                                                            texImage->RowStride);
+   const GLuint row_stride =
+      _mesa_format_row_stride(texImage->TexFormat, texImage->Width);
    GLuint i;
+   GLubyte *src;
+   GLint srcRowStride;
 
    if (_mesa_is_bufferobj(ctx->Pack.BufferObj)) {
       /* pack texture image into a PBO */
@@ -507,25 +564,32 @@ _mesa_get_compressed_teximage(struct gl_context *ctx, GLenum target, GLint level
       img = ADD_POINTERS(buf, img);
    }
 
+   /* map src texture buffer */
+   ctx->Driver.MapTextureImage(ctx, texImage, 0,
+                               0, 0, texImage->Width, texImage->Height,
+                               GL_MAP_READ_BIT, &src, &srcRowStride);
+
    /* no pixelstore or pixel transfer, but respect stride */
 
-   if (row_stride == row_stride_stored) {
+   if (row_stride == srcRowStride) {
       const GLuint size = _mesa_format_image_size(texImage->TexFormat,
                                                   texImage->Width,
                                                   texImage->Height,
                                                   texImage->Depth);
-      memcpy(img, texImage->Data, size);
+      memcpy(img, src, size);
    }
    else {
       GLuint bw, bh;
       _mesa_get_format_block_size(texImage->TexFormat, &bw, &bh);
       for (i = 0; i < (texImage->Height + bh - 1) / bh; i++) {
          memcpy((GLubyte *)img + i * row_stride,
-                (GLubyte *)texImage->Data + i * row_stride_stored,
+                (GLubyte *)src + i * srcRowStride,
                 row_stride);
       }
    }
 
+   ctx->Driver.UnmapTextureImage(ctx, texImage, 0);
+
    if (_mesa_is_bufferobj(ctx->Pack.BufferObj)) {
       ctx->Driver.UnmapBuffer(ctx, ctx->Pack.BufferObj);
    }
diff --git a/mesalib/src/mesa/main/version.c b/mesalib/src/mesa/main/version.c
index 384281479..a5deeabd2 100644
--- a/mesalib/src/mesa/main/version.c
+++ b/mesalib/src/mesa/main/version.c
@@ -27,7 +27,29 @@
 #include "version.h"
 #include "git_sha1.h"
 
+/**
+ * Override the context's GL version if the environment variable
+ * MESA_GL_VERSION_OVERRIDE is set. Valid values of MESA_GL_VERSION_OVERRIDE
+ * are point-separated version numbers, such as "3.0".
+ */
+static void
+override_version(struct gl_context *ctx, GLuint *major, GLuint *minor)
+{
+   const char *env_var = "MESA_GL_VERSION_OVERRIDE";
+   const char *version;
+   int n;
+
+   version = getenv(env_var);
+   if (!version) {
+      return;
+   }
 
+   n = sscanf(version, "%d.%d", major, minor);
+   if (n != 2) {
+      fprintf(stderr, "error: invalid value for %s: %s\n", env_var, version);
+      return;
+   }
+}
 
 /**
  * Examine enabled GL extensions to determine GL version.
@@ -178,6 +200,9 @@ compute_version(struct gl_context *ctx)
 
    ctx->VersionMajor = major;
    ctx->VersionMinor = minor;
+
+   override_version(ctx, &ctx->VersionMajor, &ctx->VersionMinor);
+
    ctx->VersionString = (char *) malloc(max);
    if (ctx->VersionString) {
       _mesa_snprintf(ctx->VersionString, max,