hookshot_vk.so is dlopen'ed, so every thread_local access in it went through __tls_get_addr: 2.4% of the Steam Deck's render thread in that call alone, more in the accessors around it. The back end is now built with -mtls-dialect=gnu2 on Linux (RX_VK_TLS=gd: as before), sampler_for's 128 KB per-thread table is on the heap (the TLS segment 178 -> ~48 KB), and the game starts itself again once with glibc.rtld.optional_static_tls room, so the loader places that segment in the static block where the descriptors are constant offsets (HOS_STATIC_TLS=0: not). Test: tests/test_static_tls.py.

Co-authored-by: Copilot App <[email protected]>
(cherry picked from commit e09ef4afd974e9d70881b08bb9dc062a48536c35)

@@ -2593,0 +2595,4 @@
+    // (longshot) on the heap, a thread's own: 128 KB of zeros in the module's TLS segment made it too big for the static TLS room
+    // the game reserves (host/hos_main.c static_tls_room), and every thread_local of the back end went through __tls_get_addr
+    struct Table { Entry e[2][4096]{}; };   // (gen 0: never filled; the generation starts at 1)
+    static thread_local std::unique_ptr<Table> table;

@@ -2056,0 +2060,4 @@
+   module's ~48 KB in the static block, where its TLS descriptors (nx2/build.py, -mtls-dialect=gnu2) resolve to a constant offset.
+   So the game starts itself again once, first of all, with the tunable added to GLIBC_TUNABLES. Kept as it is: HOS_STATIC_TLS=0, a
+   GLIBC_TUNABLES that names the tunable already, or an exec that failed (the game goes on without it) */
+#define HOS_STATIC_TLS_ROOM 98304

@@ -2056,0 +2062,4 @@
+   GLIBC_TUNABLES that names the tunable already, or an exec that failed (the game goes on without it) */
+#define HOS_STATIC_TLS_ROOM 98304
+static void static_tls_room(char **argv) {
+    const char *off = getenv("HOS_STATIC_TLS");

@@ -2056,0 +2065,4 @@
+    const char *off = getenv("HOS_STATIC_TLS");
+    if ((off && !strcmp(off, "0")) || env_on("HOS_STATIC_TLS_DONE")) return;
+    const char *was = getenv("GLIBC_TUNABLES");
+    if (was && strstr(was, "glibc.rtld.optional_static_tls")) return;

@@ -2056,0 +2079,4 @@
+    const ssize_t len = readlink("/proc/self/exe", self, sizeof self - 1);
+    const char *path = "/proc/self/exe";
+    if (len > 0) self[len] = 0, path = self;
+    execv(path, argv);

@@ -1184,0 +1184,4 @@
+        # was a call of __tls_get_addr: 2.4% of the Steam Deck's render thread, with the accessors around it more. A descriptor of a
+        # module whose TLS the loader placed in the static block (host/hos_main.c static_tls_room) is a constant offset, as the
+        # executable's own are. RX_VK_TLS=gd: the default model, as before)
+        vk_tls = ["-mtls-dialect=gnu2"] if LINUX and os.environ.get("RX_VK_TLS", "gnu2") != "gd" else []

@@ -102,2 +102,3 @@
 static void driver_cache_room() {}   // (host/hos_main.c: the drivers' shader caches' size, #2033)
-static void driver_cache_folder() {}   // (host/hos_main.c: the folder __GL_SHADER_DISK_CACHE_PATH names, made)
+static void driver_cache_folder() {}
+static void static_tls_room(char**) {}   // (host/hos_main.c: the static TLS restart, first in main)   // (host/hos_main.c: the folder __GL_SHADER_DISK_CACHE_PATH names, made)