vulkan/wsi: add support for detecting mit-shm pixmaps.

This just adds the xcb bits to detect is the host supports shared
shm pixmaps or whether the old paths should be used.

shm pixmaps will only be used if dri3 is available

Acked-by: Roland Scheidegger <sroland@vmware.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12482>

meson.build

@@ -1963,7 +1963,6 @@ if with_platform_x11
     dep_xext = dependency('xext')
     dep_xfixes = dependency('xfixes', version : '>= 2.0')
     dep_xcb_glx = dependency('xcb-glx', version : '>= 1.8.1')
-    dep_xcb_shm = dependency('xcb-shm')
   endif
   if (with_any_vk or with_glx == 'dri' or with_egl or
        (with_gallium_vdpau or with_gallium_xvmc or with_gallium_va or
@@ -1986,6 +1985,7 @@ if with_platform_x11
           dep_xcb_present.version().version_compare('>= 1.13'))
         pre_args += '-DHAVE_DRI3_MODIFIERS'
       endif
+      dep_xcb_shm = dependency('xcb-shm')
       dep_xcb_sync = dependency('xcb-sync')
       dep_xshmfence = dependency('xshmfence', version : '>= 1.1')
     endif

src/vulkan/meson.build

@@ -37,6 +37,7 @@ if with_platform_x11
     dep_xcb_present,
     dep_xcb_sync,
     dep_xcb_xrandr,
+    dep_xcb_shm,
     dep_xshmfence,
   ]
   vulkan_wsi_list += ['xcb', 'x11']

src/vulkan/wsi/wsi_common_x11.c

@@ -26,6 +26,7 @@
 #include <xcb/xcb.h>
 #include <xcb/dri3.h>
 #include <xcb/present.h>
+#include <xcb/shm.h>
 
 #include "util/macros.h"
 #include <stdlib.h>
@@ -47,12 +48,18 @@
 #include "wsi_common_x11.h"
 #include "wsi_common_queue.h"
 
+#ifdef HAVE_SYS_SHM_H
+#include <sys/ipc.h>
+#include <sys/shm.h>
+#endif
+
 struct wsi_x11_connection {
    bool has_dri3;
    bool has_dri3_modifiers;
    bool has_present;
    bool is_proprietary_x11;
    bool is_xwayland;
+   bool has_mit_shm;
 };
 
 struct wsi_x11 {
@@ -166,8 +173,8 @@ static struct wsi_x11_connection *
 wsi_x11_connection_create(struct wsi_device *wsi_dev,
                           xcb_connection_t *conn)
 {
-   xcb_query_extension_cookie_t dri3_cookie, pres_cookie, randr_cookie, amd_cookie, nv_cookie;
-   xcb_query_extension_reply_t *dri3_reply, *pres_reply, *randr_reply, *amd_reply, *nv_reply;
+   xcb_query_extension_cookie_t dri3_cookie, pres_cookie, randr_cookie, amd_cookie, nv_cookie, shm_cookie;
+   xcb_query_extension_reply_t *dri3_reply, *pres_reply, *randr_reply, *amd_reply, *nv_reply, *shm_reply = NULL;
    bool has_dri3_v1_2 = false;
    bool has_present_v1_2 = false;
 
@@ -181,6 +188,9 @@ wsi_x11_connection_create(struct wsi_device *wsi_dev,
    pres_cookie = xcb_query_extension(conn, 7, "Present");
    randr_cookie = xcb_query_extension(conn, 5, "RANDR");
 
+   if (wsi_dev->sw)
+      shm_cookie = xcb_query_extension(conn, 7, "MIT-SHM");
+
    /* We try to be nice to users and emit a warning if they try to use a
     * Vulkan application on a system without DRI3 enabled.  However, this ends
     * up spewing the warning when a user has, for example, both Intel
@@ -198,12 +208,16 @@ wsi_x11_connection_create(struct wsi_device *wsi_dev,
    randr_reply = xcb_query_extension_reply(conn, randr_cookie, NULL);
    amd_reply = xcb_query_extension_reply(conn, amd_cookie, NULL);
    nv_reply = xcb_query_extension_reply(conn, nv_cookie, NULL);
+   if (wsi_dev->sw)
+      shm_reply = xcb_query_extension_reply(conn, shm_cookie, NULL);
    if (!dri3_reply || !pres_reply) {
       free(dri3_reply);
       free(pres_reply);
       free(randr_reply);
       free(amd_reply);
       free(nv_reply);
+      if (wsi_dev->sw)
+         free(shm_reply);
       vk_free(&wsi_dev->instance_alloc, wsi_conn);
       return NULL;
    }
@@ -248,6 +262,32 @@ wsi_x11_connection_create(struct wsi_device *wsi_dev,
    if (nv_reply && nv_reply->present)
       wsi_conn->is_proprietary_x11 = true;
 
+   wsi_conn->has_mit_shm = false;
+   if (wsi_conn->has_dri3 && wsi_conn->has_present && wsi_dev->sw) {
+      bool has_mit_shm = shm_reply->present != 0;
+
+      xcb_shm_query_version_cookie_t ver_cookie;
+      xcb_shm_query_version_reply_t *ver_reply;
+
+      ver_cookie = xcb_shm_query_version(conn);
+      ver_reply = xcb_shm_query_version_reply(conn, ver_cookie, NULL);
+
+      has_mit_shm = ver_reply->shared_pixmaps;
+      free(ver_reply);
+      xcb_void_cookie_t cookie;
+      xcb_generic_error_t *error;
+
+      if (has_mit_shm) {
+         cookie = xcb_shm_detach_checked(conn, 0);
+         if ((error = xcb_request_check(conn, cookie))) {
+            if (error->error_code != BadRequest)
+               wsi_conn->has_mit_shm = true;
+            free(error);
+         }
+      }
+      free(shm_reply);
+   }
+
    free(dri3_reply);
    free(pres_reply);
    free(randr_reply);
@@ -799,6 +839,7 @@ struct x11_swapchain {
    struct wsi_swapchain                        base;
 
    bool                                         has_dri3_modifiers;
+   bool                                         has_mit_shm;
 
    xcb_connection_t *                           conn;
    xcb_window_t                                 window;
@@ -1632,6 +1673,7 @@ x11_surface_create_swapchain(VkIcdSurfaceBase *icd_surface,
    chain->has_present_queue = false;
    chain->status = VK_SUCCESS;
    chain->has_dri3_modifiers = wsi_conn->has_dri3_modifiers;
+   chain->has_mit_shm = wsi_conn->has_mit_shm;
 
    if (chain->extent.width != cur_width || chain->extent.height != cur_height)
        chain->status = VK_SUBOPTIMAL_KHR;