gallium: Add pipe loader for device enumeration and driver multiplexing.

The goal is to have a uniform interface to create winsys and
pipe_screen instances for any driver, exposing the device enumeration
capabilities that might be supported by the operating system (for now
there's a "drm" back-end using udev and a "sw" back-end that always
returns the same built-in devices).

The typical use case of this library will be:
>
> struct pipe_loader_device devs[n];
> struct pipe_screen *screen;
>
> pipe_loader_probe(&devs, n);
>[pick some device from the array...]
>
> screen = pipe_loader_create_screen(dev, library_search_path);
>[do something with screen...]
>
> screen->destroy(screen);
> pipe_loader_release(&devs, N);
>

A part of the code was taken from targets/gbm/pipe_loader.c, which
will be removed and replaced with calls into this library by a future
commit.

6 files changed, 656 insertions, 0 deletions

diff --git a/src/gallium/auxiliary/pipe-loader/Makefile.am b/src/gallium/auxiliary/pipe-loader/Makefile.am
new file mode 100644
index 00000000000..c63dce3fe4a
--- /dev/null
+++ b/src/gallium/auxiliary/pipe-loader/Makefile.am
@@ -0,0 +1,38 @@
+AUTOMAKE_OPTIONS = subdir-objects
+
+AM_CPPFLAGS = $(DEFINES) \
+	$(GALLIUM_PIPE_LOADER_DEFINES) \
+	-I$(top_srcdir)/include \
+	-I$(top_srcdir)/src/gallium/include \
+	-I$(top_srcdir)/src/gallium/auxiliary \
+	-I$(top_srcdir)/src/gallium/winsys
+
+AM_CFLAGS = $(PIC_FLAGS)
+
+noinst_LTLIBRARIES =
+
+if HAVE_LOADER_GALLIUM
+noinst_LTLIBRARIES += libpipe_loader.la
+
+libpipe_loader_la_SOURCES = \
+	pipe_loader.h \
+	pipe_loader_priv.h \
+	pipe_loader.c \
+	pipe_loader_sw.c
+
+if HAVE_DRM_LOADER_GALLIUM
+libpipe_loader_la_SOURCES += pipe_loader_drm.c
+AM_CFLAGS += $(LIBDRM_CFLAGS)
+endif
+
+# Provide compatibility with scripts for the old Mesa build system for
+# a while by putting a link to the library in the current directory.
+all-local: libpipe_loader.la
+	ln -f .libs/libpipe_loader.a .
+
+clean-local:
+	rm -f libpipe_loader.a
+endif
+
+# FIXME: Remove when the rest of Gallium is converted to automake.
+default: all
diff --git a/src/gallium/auxiliary/pipe-loader/pipe_loader.c b/src/gallium/auxiliary/pipe-loader/pipe_loader.c
new file mode 100644
index 00000000000..6a10ac3998d
--- /dev/null
+++ b/src/gallium/auxiliary/pipe-loader/pipe_loader.c
@@ -0,0 +1,102 @@
+/**************************************************************************
+ *
+ * Copyright 2012 Francisco Jerez
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
+ * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ **************************************************************************/
+
+#include "pipe_loader_priv.h"
+
+#include "util/u_inlines.h"
+#include "util/u_memory.h"
+#include "util/u_string.h"
+#include "util/u_dl.h"
+
+#define MODULE_PREFIX "pipe_"
+
+static int (*backends[])(struct pipe_loader_device **, int) = {
+#ifdef HAVE_PIPE_LOADER_DRM
+   &pipe_loader_drm_probe,
+#endif
+   &pipe_loader_sw_probe
+};
+
+int
+pipe_loader_probe(struct pipe_loader_device **devs, int ndev)
+{
+   int i, n = 0;
+
+   for (i = 0; i < Elements(backends); i++)
+      n += backends[i](&devs[n], MAX2(0, ndev - n));
+
+   return n;
+}
+
+void
+pipe_loader_release(struct pipe_loader_device **devs, int ndev)
+{
+   int i;
+
+   for (i = 0; i < ndev; i++)
+      devs[i]->ops->release(&devs[i]);
+}
+
+struct pipe_screen *
+pipe_loader_create_screen(struct pipe_loader_device *dev,
+                          const char *library_paths)
+{
+   return dev->ops->create_screen(dev, library_paths);
+}
+
+struct util_dl_library *
+pipe_loader_find_module(struct pipe_loader_device *dev,
+                        const char *library_paths)
+{
+   struct util_dl_library *lib;
+   const char *next;
+   char path[PATH_MAX];
+   int len, ret;
+
+   for (next = library_paths; *next; library_paths = next + 1) {
+      next = util_strchrnul(library_paths, ':');
+      len = next - library_paths;
+
+      if (len)
+         ret = util_snprintf(path, sizeof(path), "%.*s/%s%s%s",
+                             len, library_paths,
+                             MODULE_PREFIX, dev->driver_name, UTIL_DL_EXT);
+      else
+         ret = util_snprintf(path, sizeof(path), "%s%s%s",
+                             MODULE_PREFIX, dev->driver_name, UTIL_DL_EXT);
+
+      if (ret > 0 && ret < sizeof(path)) {
+         lib = util_dl_open(path);
+         if (lib) {
+            debug_printf("loaded %s\n", path);
+            return lib;
+         }
+      }
+   }
+
+   return NULL;
+}
diff --git a/src/gallium/auxiliary/pipe-loader/pipe_loader.h b/src/gallium/auxiliary/pipe-loader/pipe_loader.h
new file mode 100644
index 00000000000..e41969458dd
--- /dev/null
+++ b/src/gallium/auxiliary/pipe-loader/pipe_loader.h
@@ -0,0 +1,144 @@
+/**************************************************************************
+ *
+ * Copyright 2012 Francisco Jerez
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
+ * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ **************************************************************************/
+
+/**
+ * \file Library that provides device enumeration and creation of
+ * winsys/pipe_screen instances.
+ */
+
+#ifndef PIPE_LOADER_H
+#define PIPE_LOADER_H
+
+#include "pipe/p_compiler.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct pipe_screen;
+
+enum pipe_loader_device_type {
+   PIPE_LOADER_DEVICE_SOFTWARE,
+   PIPE_LOADER_DEVICE_PCI,
+   NUM_PIPE_LOADER_DEVICE_TYPES
+};
+
+/**
+ * A device known to the pipe loader.
+ */
+struct pipe_loader_device {
+   enum pipe_loader_device_type type;
+
+   union {
+      struct {
+         int vendor_id;
+         int chip_id;
+      } pci;
+   }; /**< Discriminated by \a type */
+
+   const char *driver_name;
+   const struct pipe_loader_ops *ops;
+};
+
+/**
+ * Get a list of known devices.
+ *
+ * \param devs Array that will be filled with pointers to the devices
+ *             available in the system.
+ * \param ndev Maximum number of devices to return.
+ * \return Number of devices available in the system.
+ */
+int
+pipe_loader_probe(struct pipe_loader_device **devs, int ndev);
+
+/**
+ * Create a pipe_screen for the specified device.
+ *
+ * \param dev Device the screen will be created for.
+ * \param library_paths Colon-separated list of filesystem paths that
+ *                      will be used to look for the pipe driver
+ *                      module that handles this device.
+ */
+struct pipe_screen *
+pipe_loader_create_screen(struct pipe_loader_device *dev,
+                          const char *library_paths);
+
+/**
+ * Release resources allocated for a list of devices.
+ *
+ * Should be called when the specified devices are no longer in use to
+ * release any resources allocated by pipe_loader_probe.
+ *
+ * \param devs Devices to release.
+ * \param ndev Number of devices to release.
+ */
+void
+pipe_loader_release(struct pipe_loader_device **devs, int ndev);
+
+#ifdef HAVE_PIPE_LOADER_SW
+
+/**
+ * Get a list of known software devices.
+ *
+ * This function is platform-specific.
+ *
+ * \sa pipe_loader_probe
+ */
+int
+pipe_loader_sw_probe(struct pipe_loader_device **devs, int ndev);
+
+#endif
+
+#ifdef HAVE_PIPE_LOADER_DRM
+
+/**
+ * Get a list of known DRM devices.
+ *
+ * This function is platform-specific.
+ *
+ * \sa pipe_loader_probe
+ */
+int
+pipe_loader_drm_probe(struct pipe_loader_device **devs, int ndev);
+
+/**
+ * Initialize a DRM device in an already opened fd.
+ *
+ * This function is platform-specific.
+ *
+ * \sa pipe_loader_probe
+ */
+boolean
+pipe_loader_drm_probe_fd(struct pipe_loader_device **dev, int fd);
+
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* PIPE_LOADER_H */
diff --git a/src/gallium/auxiliary/pipe-loader/pipe_loader_drm.c b/src/gallium/auxiliary/pipe-loader/pipe_loader_drm.c
new file mode 100644
index 00000000000..7a7e9942f3b
--- /dev/null
+++ b/src/gallium/auxiliary/pipe-loader/pipe_loader_drm.c
@@ -0,0 +1,218 @@
+/**************************************************************************
+ *
+ * Copyright 2011 Intel Corporation
+ * Copyright 2012 Francisco Jerez
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
+ * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * Authors:
+ *    Kristian Høgsberg <[email protected]>
+ *    Benjamin Franzke <[email protected]>
+ *
+ **************************************************************************/
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <libudev.h>
+#include <xf86drm.h>
+
+#include "state_tracker/drm_driver.h"
+#include "pipe_loader_priv.h"
+
+#include "util/u_memory.h"
+#include "util/u_dl.h"
+#include "util/u_debug.h"
+
+#define DRIVER_MAP_GALLIUM_ONLY
+#include "pci_ids/pci_id_driver_map.h"
+
+struct pipe_loader_drm_device {
+   struct pipe_loader_device base;
+   struct util_dl_library *lib;
+   int fd;
+};
+
+#define pipe_loader_drm_device(dev) ((struct pipe_loader_drm_device *)dev)
+
+static boolean
+find_drm_pci_id(struct pipe_loader_drm_device *ddev)
+{
+   struct udev *udev = NULL;
+   struct udev_device *parent, *device = NULL;
+   struct stat stat;
+   const char *pci_id;
+
+   if (fstat(ddev->fd, &stat) < 0)
+      goto fail;
+
+   udev = udev_new();
+   if (!udev)
+      goto fail;
+
+   device = udev_device_new_from_devnum(udev, 'c', stat.st_rdev);
+   if (!device)
+      goto fail;
+
+   parent = udev_device_get_parent(device);
+   if (!parent)
+      goto fail;
+
+   pci_id = udev_device_get_property_value(parent, "PCI_ID");
+   if (!pci_id ||
+       sscanf(pci_id, "%x:%x", &ddev->base.pci.vendor_id,
+              &ddev->base.pci.chip_id) != 2)
+      goto fail;
+
+   return TRUE;
+
+  fail:
+   if (device)
+      udev_device_unref(device);
+   if (udev)
+      udev_unref(udev);
+
+   debug_printf("pci id for fd %d not found\n", ddev->fd);
+   return FALSE;
+}
+
+static boolean
+find_drm_driver_name(struct pipe_loader_drm_device *ddev)
+{
+   struct pipe_loader_device *dev = &ddev->base;
+   int i, j;
+
+   for (i = 0; driver_map[i].driver; i++) {
+      if (dev->pci.vendor_id != driver_map[i].vendor_id)
+         continue;
+
+      if (driver_map[i].num_chips_ids == -1) {
+         dev->driver_name = driver_map[i].driver;
+         goto found;
+      }
+
+      for (j = 0; j < driver_map[i].num_chips_ids; j++) {
+         if (dev->pci.chip_id == driver_map[i].chip_ids[j]) {
+            dev->driver_name = driver_map[i].driver;
+            goto found;
+         }
+      }
+   }
+
+   return FALSE;
+
+  found:
+   debug_printf("driver for %04x:%04x: %s\n", dev->pci.vendor_id,
+                dev->pci.chip_id, dev->driver_name);
+   return TRUE;
+}
+
+static struct pipe_loader_ops pipe_loader_drm_ops;
+
+boolean
+pipe_loader_drm_probe_fd(struct pipe_loader_device **dev, int fd)
+{
+   struct pipe_loader_drm_device *ddev = CALLOC_STRUCT(pipe_loader_drm_device);
+
+   ddev->base.type = PIPE_LOADER_DEVICE_PCI;
+   ddev->base.ops = &pipe_loader_drm_ops;
+   ddev->fd = fd;
+
+   if (!find_drm_pci_id(ddev))
+      goto fail;
+
+   if (!find_drm_driver_name(ddev))
+      goto fail;
+
+   *dev = &ddev->base;
+   return TRUE;
+
+  fail:
+   FREE(ddev);
+   return FALSE;
+}
+
+static int
+open_drm_minor(int minor)
+{
+   char path[PATH_MAX];
+   snprintf(path, sizeof(path), DRM_DEV_NAME, DRM_DIR_NAME, minor);
+   return open(path, O_RDWR, 0);
+}
+
+int
+pipe_loader_drm_probe(struct pipe_loader_device **devs, int ndev)
+{
+   int i, j, fd;
+
+   for (i = 0, j = 0; i < DRM_MAX_MINOR; i++) {
+      fd = open_drm_minor(i);
+      if (fd < 0)
+         continue;
+
+      if (j >= ndev || !pipe_loader_drm_probe_fd(&devs[j], fd))
+         close(fd);
+
+      j++;
+   }
+
+   return j;
+}
+
+static void
+pipe_loader_drm_release(struct pipe_loader_device **dev)
+{
+   struct pipe_loader_drm_device *ddev = pipe_loader_drm_device(*dev);
+
+   if (ddev->lib)
+      util_dl_close(ddev->lib);
+
+   close(ddev->fd);
+   FREE(ddev);
+   *dev = NULL;
+}
+
+static struct pipe_screen *
+pipe_loader_drm_create_screen(struct pipe_loader_device *dev,
+                              const char *library_paths)
+{
+   struct pipe_loader_drm_device *ddev = pipe_loader_drm_device(dev);
+   const struct drm_driver_descriptor *dd;
+
+   if (!ddev->lib)
+      ddev->lib = pipe_loader_find_module(dev, library_paths);
+   if (!ddev->lib)
+      return NULL;
+
+   dd = (const struct drm_driver_descriptor *)
+      util_dl_get_proc_address(ddev->lib, "driver_descriptor");
+
+   /* sanity check on the name */
+   if (!dd || strcmp(dd->name, ddev->base.driver_name) != 0)
+      return NULL;
+
+   return dd->create_screen(ddev->fd);
+}
+
+static struct pipe_loader_ops pipe_loader_drm_ops = {
+   .create_screen = pipe_loader_drm_create_screen,
+   .release = pipe_loader_drm_release
+};
diff --git a/src/gallium/auxiliary/pipe-loader/pipe_loader_priv.h b/src/gallium/auxiliary/pipe-loader/pipe_loader_priv.h
new file mode 100644
index 00000000000..0be833a0f3f
--- /dev/null
+++ b/src/gallium/auxiliary/pipe-loader/pipe_loader_priv.h
@@ -0,0 +1,47 @@
+/**************************************************************************
+ *
+ * Copyright 2012 Francisco Jerez
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
+ * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ **************************************************************************/
+
+#ifndef PIPE_LOADER_PRIV_H
+#define PIPE_LOADER_PRIV_H
+
+#include "pipe_loader.h"
+
+struct pipe_loader_ops {
+   struct pipe_screen *(*create_screen)(struct pipe_loader_device *dev,
+                                        const char *library_paths);
+
+   void (*release)(struct pipe_loader_device **dev);
+};
+
+/**
+ * Open the pipe driver module that handles a specified device.
+ */
+struct util_dl_library *
+pipe_loader_find_module(struct pipe_loader_device *dev,
+                        const char *library_paths);
+
+#endif /* PIPE_LOADER_PRIV_H */
diff --git a/src/gallium/auxiliary/pipe-loader/pipe_loader_sw.c b/src/gallium/auxiliary/pipe-loader/pipe_loader_sw.c
new file mode 100644
index 00000000000..c2b78c636a7
--- /dev/null
+++ b/src/gallium/auxiliary/pipe-loader/pipe_loader_sw.c
@@ -0,0 +1,107 @@
+/**************************************************************************
+ *
+ * Copyright 2012 Francisco Jerez
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
+ * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ **************************************************************************/
+
+#include "pipe_loader_priv.h"
+
+#include "util/u_memory.h"
+#include "util/u_dl.h"
+#include "sw/null/null_sw_winsys.h"
+#include "target-helpers/inline_sw_helper.h"
+#include "state_tracker/xlib_sw_winsys.h"
+
+struct pipe_loader_sw_device {
+   struct pipe_loader_device base;
+   struct util_dl_library *lib;
+   struct sw_winsys *ws;
+};
+
+#define pipe_loader_sw_device(dev) ((struct pipe_loader_sw_device *)dev)
+
+static struct pipe_loader_ops pipe_loader_sw_ops;
+
+static struct sw_winsys *(*backends[])() = {
+#ifdef HAVE_WINSYS_XLIB
+   x11_sw_create,
+#endif
+   null_sw_create
+};
+
+int
+pipe_loader_sw_probe(struct pipe_loader_device **devs, int ndev)
+{
+   int i;
+
+   for (i = 0; i < Elements(backends); i++) {
+      if (i < ndev) {
+         struct pipe_loader_sw_device *sdev = CALLOC_STRUCT(pipe_loader_sw_device);
+
+         sdev->base.type = PIPE_LOADER_DEVICE_SOFTWARE;
+         sdev->base.driver_name = "swrast";
+         sdev->base.ops = &pipe_loader_sw_ops;
+         sdev->ws = backends[i]();
+         devs[i] = &sdev->base;
+      }
+   }
+
+   return i;
+}
+
+static void
+pipe_loader_sw_release(struct pipe_loader_device **dev)
+{
+   struct pipe_loader_sw_device *sdev = pipe_loader_sw_device(*dev);
+
+   if (sdev->lib)
+      util_dl_close(sdev->lib);
+
+   FREE(sdev);
+   *dev = NULL;
+}
+
+static struct pipe_screen *
+pipe_loader_sw_create_screen(struct pipe_loader_device *dev,
+                             const char *library_paths)
+{
+   struct pipe_loader_sw_device *sdev = pipe_loader_sw_device(dev);
+   struct pipe_screen *(*init)(struct sw_winsys *);
+
+   if (!sdev->lib)
+      sdev->lib = pipe_loader_find_module(dev, library_paths);
+   if (!sdev->lib)
+      return NULL;
+
+   init = (void *)util_dl_get_proc_address(sdev->lib, "swrast_create_screen");
+   if (!init)
+      return NULL;
+
+   return init(sdev->ws);
+}
+
+static struct pipe_loader_ops pipe_loader_sw_ops = {
+   .create_screen = pipe_loader_sw_create_screen,
+   .release = pipe_loader_sw_release
+};