File 0003-Enable-implicit-sync-if-we-re-talking-to-the-NVIDIA-.patch of Package libnvidia-egl-x11
From f0c64b0fd24b884247889cb86a343c2adf65edc7 Mon Sep 17 00:00:00 2001
From: Kyle Brenneman <kbrenneman@nvidia.com>
Date: Wed, 25 Jun 2025 17:17:15 -0600
Subject: [PATCH 4/4] Enable implicit sync if we're talking to the NVIDIA Xorg
server module.
Although the NVIDIA driver doesn't support implicit sync semantics, the
NVIDIA Xorg driver will extract and attach the fence attached to the
dma-buf when it processes a PresentPixmap or CopyArea request, which is
enough for egl-x11 to use its implicit sync path.
Thus, we can set supports_implicit_sync if the server is on a non-NV
device, or if the server is running on the NVIDIA Xorg module (which we
can check by looking for the NVIDIA-specific NV-GLX extension).
Also added some environment variables to control the sync path:
Setting __NV_X11_FORCE_IMPLICIT_SYNC=1 will force egl-x11 to enable its
implicit sync path, though it will still use explicit sync first if
that's available. Setting it to "0" will disable the implicit sync path.
Setting __NV_X11_DISABLE_EXPLICIT_SYNC=1 will disable the explicit sync
path.
---
src/x11/x11-platform.c | 62 ++++++++++++++++++++++++++++++++----------
src/x11/x11-window.c | 28 +++++++++++--------
2 files changed, 64 insertions(+), 26 deletions(-)
diff --git a/src/x11/x11-platform.c b/src/x11/x11-platform.c
index 1d73bdc..a073f34 100644
--- a/src/x11/x11-platform.c
+++ b/src/x11/x11-platform.c
@@ -709,6 +709,21 @@ static void eplX11CleanupDisplay(EplDisplay *pdpy)
}
}
+static EGLBoolean CheckX11Extension(xcb_connection_t *conn, const char *name)
+{
+ xcb_generic_error_t *error = NULL;
+ xcb_query_extension_reply_t *reply = xcb_query_extension_reply(conn,
+ xcb_query_extension(conn, strlen(name), name), &error);
+ EGLBoolean ret = EGL_FALSE;
+ if (reply != NULL)
+ {
+ ret = (reply->present != 0);
+ free(reply);
+ }
+ free(error);
+ return ret;
+}
+
/**
* Checks whether the server has the necessary support that we need.
*
@@ -727,7 +742,6 @@ static EGLBoolean CheckServerExtensions(X11DisplayInstance *inst)
xcb_dri3_query_version_reply_t *dri3Reply = NULL;
xcb_present_query_version_cookie_t presentCookie;
xcb_present_query_version_reply_t *presentReply = NULL;
- xcb_query_extension_reply_t *nvglxReply = NULL;
EGLBoolean success = EGL_FALSE;
// Check to make sure that we're using a domain socket, since we need to be
@@ -765,17 +779,7 @@ static EGLBoolean CheckServerExtensions(X11DisplayInstance *inst)
* we could add some requests to NV-GLX to support older (pre DRI3 1.2)
* servers or non-Linux systems.
*/
- const char NVGLX_EXTENSION_NAME[] = "NV-GLX";
- xcb_query_extension_cookie_t extCookie = xcb_query_extension(inst->conn,
- sizeof(NVGLX_EXTENSION_NAME) - 1, NVGLX_EXTENSION_NAME);
- nvglxReply = xcb_query_extension_reply(inst->conn, extCookie, &error);
- if (nvglxReply == NULL)
- {
- // XQueryExtension isn't supposed to generate any errors.
- goto done;
- }
-
- if (nvglxReply->present)
+ if (CheckX11Extension(inst->conn, "NV-GLX"))
{
goto done;
}
@@ -821,7 +825,6 @@ static EGLBoolean CheckServerExtensions(X11DisplayInstance *inst)
success = EGL_TRUE;
done:
- free(nvglxReply);
free(presentReply);
free(dri3Reply);
free(error);
@@ -893,6 +896,7 @@ X11DisplayInstance *eplX11DisplayInstanceCreate(EplDisplay *pdpy, EGLBoolean fro
EplInternalDisplay *internalDpy = NULL;
EGLBoolean supportsDirect = EGL_FALSE;
EGLBoolean supportsLinear = EGL_FALSE;
+ const char *env;
inst = calloc(1, sizeof(X11DisplayInstance));
if (inst == NULL)
@@ -1013,7 +1017,15 @@ X11DisplayInstance *eplX11DisplayInstanceCreate(EplDisplay *pdpy, EGLBoolean fro
return NULL;
}
- inst->supports_implicit_sync = EGL_FALSE;
+ /*
+ * The NVIDIA driver does not support implicit sync semantics in OpenGL
+ * and similar. However, if the NVIDIA server-side driver module for
+ * Xorg supports DRI3 1.2, then it will will extract and attach fences
+ * from the dma-buf when it processes a PresentPixmap or CopyArea
+ * request, which is all we actually need in order to use our implicit
+ * sync path.
+ */
+ inst->supports_implicit_sync = CheckX11Extension(inst->conn, "NV-GLX");
}
else
{
@@ -1047,6 +1059,19 @@ X11DisplayInstance *eplX11DisplayInstanceCreate(EplDisplay *pdpy, EGLBoolean fro
inst->supports_implicit_sync = EGL_TRUE;
}
+ env = getenv("__NV_X11_FORCE_IMPLICIT_SYNC");
+ if (env != NULL)
+ {
+ if (strcmp(env, "1") == 0)
+ {
+ inst->supports_implicit_sync = EGL_TRUE;
+ }
+ else if (strcmp(env, "0") == 0)
+ {
+ inst->supports_implicit_sync = EGL_FALSE;
+ }
+ }
+
if (inst->device == EGL_NO_DEVICE_EXT)
{
if (from_init)
@@ -1192,6 +1217,15 @@ X11DisplayInstance *eplX11DisplayInstanceCreate(EplDisplay *pdpy, EGLBoolean fro
}
}
+ if (inst->supports_explicit_sync)
+ {
+ env = getenv("__NV_X11_DISABLE_EXPLICIT_SYNC");
+ if (env != NULL && atoi(env) != 0)
+ {
+ inst->supports_explicit_sync = EGL_FALSE;
+ }
+ }
+
if (inst->force_prime && !inst->supports_prime)
{
if (from_init)
diff --git a/src/x11/x11-window.c b/src/x11/x11-window.c
index 040d7bf..5a458ba 100644
--- a/src/x11/x11-window.c
+++ b/src/x11/x11-window.c
@@ -340,15 +340,14 @@ static void FreeColorBuffer(X11DisplayInstance *inst, X11ColorBuffer *buffer)
static X11ColorBuffer *AllocOneColorBuffer(X11DisplayInstance *inst,
const EplFormatInfo *fmt, uint32_t width, uint32_t height,
const uint64_t *modifiers, int num_modifiers,
- EGLBoolean scanout)
+ EGLBoolean prime)
{
- int fd = -1;
uint32_t flags = 0;
X11ColorBuffer *buffer = NULL;
assert(num_modifiers > 0);
- if (scanout)
+ if (!prime)
{
flags |= GBM_BO_USE_SCANOUT;
}
@@ -370,14 +369,14 @@ static X11ColorBuffer *AllocOneColorBuffer(X11DisplayInstance *inst,
goto done;
}
- fd = gbm_bo_get_fd(buffer->gbo);
- if (fd < 0)
+ buffer->fd = gbm_bo_get_fd(buffer->gbo);
+ if (buffer->fd < 0)
{
goto done;
}
buffer->buffer = inst->platform->priv->egl.PlatformImportColorBufferNVX(inst->internal_display->edpy,
- fd, width, height, gbm_bo_get_format(buffer->gbo),
+ buffer->fd, width, height, gbm_bo_get_format(buffer->gbo),
gbm_bo_get_stride(buffer->gbo),
gbm_bo_get_offset(buffer->gbo, 0),
gbm_bo_get_modifier(buffer->gbo));
@@ -386,11 +385,15 @@ static X11ColorBuffer *AllocOneColorBuffer(X11DisplayInstance *inst,
goto done;
}
-done:
- if (fd >= 0)
+ if (prime || !inst->supports_implicit_sync)
{
- close(fd);
+ // We only need to hold on to a file descriptor for a shared dma-buf,
+ // and only if we're using implicit sync.
+ close(buffer->fd);
+ buffer->fd = -1;
}
+
+done:
if (buffer->buffer == NULL)
{
FreeColorBuffer(inst, buffer);
@@ -497,7 +500,7 @@ static EGLBoolean AllocWindowBuffers(EplSurface *surf,
EGLBoolean success = EGL_TRUE;
front = AllocOneColorBuffer(pwin->inst, pwin->format->fmt, pwin->pending_width, pwin->pending_height,
- modifiers, num_modifiers, !prime);
+ modifiers, num_modifiers, prime);
if (front == NULL)
{
goto done;
@@ -508,7 +511,7 @@ static EGLBoolean AllocWindowBuffers(EplSurface *surf,
modifier = gbm_bo_get_modifier(front->gbo);
back = AllocOneColorBuffer(pwin->inst, pwin->format->fmt, pwin->pending_width, pwin->pending_height,
- &modifier, 1, !prime);
+ &modifier, 1, prime);
if (back == NULL)
{
goto done;
@@ -1785,6 +1788,7 @@ static int CheckBufferReleaseImplicit(EplDisplay *pdpy, EplSurface *surf,
{
if (buffer != skip && buffer->status == BUFFER_STATUS_IDLE_NOTIFIED)
{
+ assert(buffer->fd >= 0);
buffers[count] = buffer;
fds[count].fd = buffer->fd;
fds[count].events = POLLOUT;
@@ -2107,7 +2111,7 @@ static X11ColorBuffer *GetFreeBuffer(EplDisplay *pdpy, EplSurface *surf,
else
{
buffer = AllocOneColorBuffer(pwin->inst, pwin->format->fmt, pwin->width, pwin->height,
- &pwin->modifier, 1, !pwin->prime);
+ &pwin->modifier, 1, pwin->prime);
}
if (buffer == NULL)
{
--
2.51.0
