glx/dri2: Add support for GLX_ARB_create_context_robustness

Add the infrastructure required for this extension.  There is no
xserver support and no driver support yet.  Drivers can enable this be
advertising DRI2 version 4 and accepting the
__DRI_CTX_FLAG_ROBUST_BUFFER_ACCESS flag and the
__DRI_CTX_ATTRIB_RESET_STRATEGY attribute in create context.

Some additional Mesa infrastructure is needed before drivers can do
this.  The GL_ARB_robustness spec, which all Mesa drivers already
advertise, requires:

    "If the behavior is LOSE_CONTEXT_ON_RESET_ARB, a graphics reset
    will result in the loss of all context state, requiring the
    recreation of all associated objects."

It is necessary to land this infrastructure now so that the related
infrastructure can land in the xserver.  The xserver has very long
release schedules, and the remaining Mesa parts should land long, long
before the next xserver merge window opens.

v2: Expose robustness as a DRI2 extension rather than bumping
__DRI_DRI2_VERSION.

v3: Add a comment explaining why dri2->base.version >= 3 is also
required for GLX_ARB_create_context_robustness.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>

7 files changed, 84 insertions, 6 deletions

diff --git a/include/GL/internal/dri_interface.h b/include/GL/internal/dri_interface.h
index e37917e..29c9a11 100644
--- a/include/GL/internal/dri_interface.h
+++ b/include/GL/internal/dri_interface.h
@@ -808,10 +808,28 @@ struct __DRIdri2LoaderExtensionRec {
 #define __DRI_CTX_ATTRIB_MINOR_VERSION		1
 #define __DRI_CTX_ATTRIB_FLAGS			2
 
+/**
+ * \requires __DRI2_ROBUSTNESS.
+ */
+#define __DRI_CTX_ATTRIB_RESET_STRATEGY		3
+
 #define __DRI_CTX_FLAG_DEBUG			0x00000001
 #define __DRI_CTX_FLAG_FORWARD_COMPATIBLE	0x00000002
 
 /**
+ * \requires __DRI2_ROBUSTNESS.
+ */
+#define __DRI_CTX_FLAG_ROBUST_BUFFER_ACCESS	0x00000004
+
+/**
+ * \name Context reset strategies.
+ */
+/*@{*/
+#define __DRI_CTX_RESET_NO_NOTIFICATION		0
+#define __DRI_CTX_RESET_LOSE_CONTEXT		1
+/*@}*/
+
+/**
  * \name Reasons that __DRIdri2Extension::createContextAttribs might fail
  */
 /*@{*/
@@ -1000,4 +1018,21 @@ struct __DRI2configQueryExtensionRec {
    int (*configQueryi)(__DRIscreen *screen, const char *var, GLint *val);
    int (*configQueryf)(__DRIscreen *screen, const char *var, GLfloat *val);
 };
+
+/**
+ * Robust context driver extension.
+ *
+ * Existence of this extension means the driver can accept the
+ * \c __DRI_CTX_FLAG_ROBUST_BUFFER_ACCESS flag and the
+ * \c __DRI_CTX_ATTRIB_RESET_STRATEGY attribute in
+ * \c __DRIdri2ExtensionRec::createContextAttribs.
+ */
+#define __DRI2_ROBUSTNESS "DRI_Robustness"
+#define __DRI2_ROBUSTNESS_VERSION 1
+
+typedef struct __DRIrobustnessExtensionRec __DRIrobustnessExtension;
+struct __DRIrobustnessExtensionRec {
+   __DRIextension base;
+};
+
 #endif
diff --git a/src/glx/dri2_glx.c b/src/glx/dri2_glx.c
index b6988c3..79237c3 100644
--- a/src/glx/dri2_glx.c
+++ b/src/glx/dri2_glx.c
@@ -241,7 +241,8 @@ dri2_create_context_attribs(struct glx_screen *base,
    uint32_t major_ver = 2;
    uint32_t flags = 0;
    unsigned api;
-   uint32_t ctx_attribs[2 * 4];
+   int reset;
+   uint32_t ctx_attribs[2 * 5];
    unsigned num_ctx_attribs = 0;
 
    if (psc->dri2->base.version < 3) {
@@ -252,7 +253,8 @@ dri2_create_context_attribs(struct glx_screen *base,
    /* Remap the GLX tokens to DRI2 tokens.
     */
    if (!dri2_convert_glx_attribs(num_attribs, attribs,
-				 &major_ver, &minor_ver, &flags, &api, error))
+				 &major_ver, &minor_ver, &flags, &api, &reset,
+                                 error))
       goto error_exit;
 
    if (shareList) {
@@ -275,6 +277,15 @@ dri2_create_context_attribs(struct glx_screen *base,
    ctx_attribs[num_ctx_attribs++] = __DRI_CTX_ATTRIB_MINOR_VERSION;
    ctx_attribs[num_ctx_attribs++] = minor_ver;
 
+   /* Only send a value when the non-default value is requested.  By doing
+    * this we don't have to check the driver's DRI2 version before sending the
+    * default value.
+    */
+   if (reset != __DRI_CTX_RESET_NO_NOTIFICATION) {
+      ctx_attribs[num_ctx_attribs++] = __DRI_CTX_ATTRIB_RESET_STRATEGY;
+      ctx_attribs[num_ctx_attribs++] = reset;
+   }
+
    if (flags != 0) {
       ctx_attribs[num_ctx_attribs++] = __DRI_CTX_ATTRIB_FLAGS;
 
@@ -979,6 +990,14 @@ dri2BindExtensions(struct dri2_screen *psc, const __DRIextension **extensions)
 
       if (((strcmp(extensions[i]->name, __DRI2_THROTTLE) == 0)))
 	 psc->throttle = (__DRI2throttleExtension *) extensions[i];
+
+      /* DRI2 version 3 is also required because
+       * GLX_ARB_create_context_robustness requires GLX_ARB_create_context.
+       */
+      if (psc->dri2->base.version >= 3
+          && strcmp(extensions[i]->name, __DRI2_ROBUSTNESS) == 0)
+         __glXEnableDirectExtension(&psc->base,
+                                    "GLX_ARB_create_context_robustness");
    }
 }
 
diff --git a/src/glx/dri_common.c b/src/glx/dri_common.c
index 07fd015..d170aa6 100644
--- a/src/glx/dri_common.c
+++ b/src/glx/dri_common.c
@@ -457,7 +457,8 @@ driReleaseDrawables(struct glx_context *gc)
 _X_HIDDEN bool
 dri2_convert_glx_attribs(unsigned num_attribs, const uint32_t *attribs,
 			 unsigned *major_ver, unsigned *minor_ver,
-			 uint32_t *flags, unsigned *api, unsigned *error)
+			 uint32_t *flags, unsigned *api, int *reset,
+                         unsigned *error)
 {
    unsigned i;
    bool got_profile = false;
@@ -478,6 +479,7 @@ dri2_convert_glx_attribs(unsigned num_attribs, const uint32_t *attribs,
 
    *major_ver = 1;
    *minor_ver = 0;
+   *reset = __DRI_CTX_RESET_NO_NOTIFICATION;
 
    for (i = 0; i < num_attribs; i++) {
       switch (attribs[i * 2]) {
@@ -497,6 +499,19 @@ dri2_convert_glx_attribs(unsigned num_attribs, const uint32_t *attribs,
       case GLX_RENDER_TYPE:
 	 render_type = attribs[i * 2 + 1];
 	 break;
+      case GLX_CONTEXT_RESET_NOTIFICATION_STRATEGY_ARB:
+         switch (attribs[i * 2 + 1]) {
+         case GLX_NO_RESET_NOTIFICATION_ARB:
+            *reset = __DRI_CTX_RESET_NO_NOTIFICATION;
+            break;
+         case GLX_LOSE_CONTEXT_ON_RESET_ARB:
+            *reset = __DRI_CTX_RESET_LOSE_CONTEXT;
+            break;
+         default:
+            *error = __DRI_CTX_ERROR_UNKNOWN_ATTRIBUTE;
+            return false;
+         }
+         break;
       default:
 	 /* If an unknown attribute is received, fail.
 	  */
@@ -536,7 +551,8 @@ dri2_convert_glx_attribs(unsigned num_attribs, const uint32_t *attribs,
 
    /* Unknown flag value.
     */
-   if (*flags & ~(__DRI_CTX_FLAG_DEBUG | __DRI_CTX_FLAG_FORWARD_COMPATIBLE)) {
+   if (*flags & ~(__DRI_CTX_FLAG_DEBUG | __DRI_CTX_FLAG_FORWARD_COMPATIBLE
+                  | __DRI_CTX_FLAG_ROBUST_BUFFER_ACCESS)) {
       *error = __DRI_CTX_ERROR_UNKNOWN_FLAG;
       return false;
    }
diff --git a/src/glx/dri_common.h b/src/glx/dri_common.h
index f5c7d45..93cd744 100644
--- a/src/glx/dri_common.h
+++ b/src/glx/dri_common.h
@@ -72,6 +72,7 @@ extern void *driOpenDriver(const char *driverName);
 extern bool
 dri2_convert_glx_attribs(unsigned num_attribs, const uint32_t *attribs,
 			 unsigned *major_ver, unsigned *minor_ver,
-			 uint32_t *flags, unsigned *api, unsigned *error);
+			 uint32_t *flags, unsigned *api, int *reset,
+			 unsigned *error);
 
 #endif /* _DRI_COMMON_H */
diff --git a/src/glx/drisw_glx.c b/src/glx/drisw_glx.c
index 95d2dcc..519786e 100644
--- a/src/glx/drisw_glx.c
+++ b/src/glx/drisw_glx.c
@@ -433,6 +433,7 @@ drisw_create_context_attribs(struct glx_screen *base,
    uint32_t major_ver = 0;
    uint32_t flags = 0;
    unsigned api;
+   int reset;
    uint32_t ctx_attribs[2 * 4];
    unsigned num_ctx_attribs = 0;
 
@@ -445,10 +446,13 @@ drisw_create_context_attribs(struct glx_screen *base,
    /* Remap the GLX tokens to DRI2 tokens.
     */
    if (!dri2_convert_glx_attribs(num_attribs, attribs,
-				 &major_ver, &minor_ver, &flags, &api,
+				 &major_ver, &minor_ver, &flags, &api, &reset,
 				 error))
       return NULL;
 
+   if (reset != __DRI_CTX_RESET_NO_NOTIFICATION)
+      return NULL;
+
    if (shareList) {
       pcp_shared = (struct drisw_context *) shareList;
       shared = pcp_shared->driContext;
diff --git a/src/glx/glxextensions.c b/src/glx/glxextensions.c
index 86dc7d0..9ddc39d 100644
--- a/src/glx/glxextensions.c
+++ b/src/glx/glxextensions.c
@@ -74,9 +74,11 @@ static const struct extension_info known_glx_extensions[] = {
 #ifdef HAVE_XCB_GLX_CREATE_CONTEXT
    { GLX(ARB_create_context),          VER(0,0), Y, N, N, N },
    { GLX(ARB_create_context_profile),  VER(0,0), Y, N, N, N },
+   { GLX(ARB_create_context_robustness), VER(0,0), Y, N, N, N },
 #else
    { GLX(ARB_create_context),          VER(0,0), N, N, N, N },
    { GLX(ARB_create_context_profile),  VER(0,0), N, N, N, N },
+   { GLX(ARB_create_context_robustness), VER(0,0), N, N, N, N },
 #endif
    { GLX(ARB_get_proc_address),        VER(1,4), Y, N, Y, N },
    { GLX(ARB_multisample),             VER(1,4), Y, Y, N, N },
diff --git a/src/glx/glxextensions.h b/src/glx/glxextensions.h
index cad69a8..90c27a7 100644
--- a/src/glx/glxextensions.h
+++ b/src/glx/glxextensions.h
@@ -35,6 +35,7 @@ enum
 {
    ARB_create_context_bit = 0,
    ARB_create_context_profile_bit,
+   ARB_create_context_robustness_bit,
    ARB_get_proc_address_bit,
    ARB_multisample_bit,
    ATI_pixel_format_float_bit,