[Mesa-dev] [PATCH RFC 2/4] dri: Optionally turn off a couple of GLX extensions based on driconf options

[Thomas Hellstrom]

With GLX_EXT_buffer_age turned on, gnome-shell will use full-screen damage
with GLX, which severely hurts performance with architectures that emulate
page-flips with copies. Like vmware. We would like to be able to turn off that
extension. Similarly, typically the GLX_OML_sync_control doesn't make much
sense on a virtual architecture since we don't really sync to the host's
vertical retrace. We'd like to be able to turn it off as well.

Signed-off-by: Thomas Hellstrom <thellstrom at vmware.com>
---
 src/glx/dri2_glx.c                              |  7 ++++++-
 src/glx/dri3_glx.c                              | 11 +++++++++--
 src/mesa/drivers/dri/common/xmlpool/t_options.h | 10 ++++++++++
 3 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/src/glx/dri2_glx.c b/src/glx/dri2_glx.c
index 145f44d..f17de01 100644
--- a/src/glx/dri2_glx.c
+++ b/src/glx/dri2_glx.c
@@ -1298,12 +1298,17 @@ dri2CreateScreen(int screen, struct glx_display * priv)
    psp->getBufferAge = NULL;
 
    if (pdp->driMinor >= 2) {
+      unsigned char disable;
+
       psp->getDrawableMSC = dri2DrawableGetMSC;
       psp->waitForMSC = dri2WaitForMSC;
       psp->waitForSBC = dri2WaitForSBC;
       psp->setSwapInterval = dri2SetSwapInterval;
       psp->getSwapInterval = dri2GetSwapInterval;
-      __glXEnableDirectExtension(&psc->base, "GLX_OML_sync_control");
+      if (psc->config->configQueryb(psc->driScreen,
+                                    "glx_disable_oml_sync_control",
+                                    &disable) || !disable)
+         __glXEnableDirectExtension(&psc->base, "GLX_OML_sync_control");
    }
 
    /* DRI2 supports SubBuffer through DRI2CopyRegion, so it's always
diff --git a/src/glx/dri3_glx.c b/src/glx/dri3_glx.c
index e1dc5aa..4264fd8 100644
--- a/src/glx/dri3_glx.c
+++ b/src/glx/dri3_glx.c
@@ -780,6 +780,7 @@ dri3_create_screen(int screen, struct glx_display * priv)
    struct glx_config *configs = NULL, *visuals = NULL;
    char *driverName, *deviceName, *tmp;
    int i;
+   unsigned char disable;
 
    psc = calloc(1, sizeof *psc);
    if (psc == NULL)
@@ -918,13 +919,19 @@ dri3_create_screen(int screen, struct glx_display * priv)
    psp->waitForSBC = dri3_wait_for_sbc;
    psp->setSwapInterval = dri3_set_swap_interval;
    psp->getSwapInterval = dri3_get_swap_interval;
-   __glXEnableDirectExtension(&psc->base, "GLX_OML_sync_control");
+   if (psc->config->configQueryb(psc->driScreen,
+                                 "glx_disable_oml_sync_control",
+                                 &disable) || !disable)
+      __glXEnableDirectExtension(&psc->base, "GLX_OML_sync_control");
 
    psp->copySubBuffer = dri3_copy_sub_buffer;
    __glXEnableDirectExtension(&psc->base, "GLX_MESA_copy_sub_buffer");
 
    psp->getBufferAge = dri3_get_buffer_age;
-   __glXEnableDirectExtension(&psc->base, "GLX_EXT_buffer_age");
+   if (psc->config->configQueryb(psc->driScreen,
+                                 "glx_disable_ext_buffer_age",
+                                 &disable) || !disable)
+      __glXEnableDirectExtension(&psc->base, "GLX_EXT_buffer_age");
 
    free(driverName);
    free(deviceName);
diff --git a/src/mesa/drivers/dri/common/xmlpool/t_options.h b/src/mesa/drivers/dri/common/xmlpool/t_options.h
index cd4f025..3a8618b 100644
--- a/src/mesa/drivers/dri/common/xmlpool/t_options.h
+++ b/src/mesa/drivers/dri/common/xmlpool/t_options.h
@@ -323,6 +323,16 @@ DRI_CONF_OPT_BEGIN_B(mesa_glthread, def) \
         DRI_CONF_DESC(en,gettext("Enable offloading GL driver work to a separate thread")) \
 DRI_CONF_OPT_END
 
+#define DRI_CONF_DISABLE_EXT_BUFFER_AGE(def) \
+DRI_CONF_OPT_BEGIN_B(glx_disable_ext_buffer_age, def) \
+   DRI_CONF_DESC(en, gettext("Disable the GLX_EXT_buffer_age extension")) \
+DRI_CONF_OPT_END
+
+#define DRI_CONF_DISABLE_OML_SYNC_CONTROL(def) \
+DRI_CONF_OPT_BEGIN_B(glx_disable_oml_sync_control, def) \
+   DRI_CONF_DESC(en, gettext("Disable the GLX_OML_sync_control extension")) \
+DRI_CONF_OPT_END
+
 
 /**
  * \brief Software-fallback options.  To allow using features (like
-- 
2.7.4