diff --git a/CMakeLists.txt b/CMakeLists.txt
index be31379d..0c5b4eac 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -49,6 +49,19 @@ function(_rust_map_target)
     else()
       message(FATAL_ERROR "Rust: Unsupported riscv ISA")
     endif()
+  elseif(CONFIG_XTENSA)
+    # Xtensa targets exist upstream as tier 3 (rust-lang/rust #125141) but
+    # official rustc ships without the Xtensa LLVM backend; these require
+    # the esp-rs Rust toolchain on PATH.
+    if(CONFIG_SOC_SERIES_ESP32S3)
+      set(RUST_TARGET "xtensa-esp32s3-none-elf" PARENT_SCOPE)
+    elseif(CONFIG_SOC_SERIES_ESP32S2)
+      set(RUST_TARGET "xtensa-esp32s2-none-elf" PARENT_SCOPE)
+    elseif(CONFIG_SOC_SERIES_ESP32)
+      set(RUST_TARGET "xtensa-esp32-none-elf" PARENT_SCOPE)
+    else()
+      message(FATAL_ERROR "Rust: Unsupported Xtensa SoC series")
+    endif()
   elseif(CONFIG_ARCH_POSIX AND CONFIG_64BIT AND (${CMAKE_HOST_SYSTEM_PROCESSOR} MATCHES "x86_64"))
     set(RUST_TARGET "x86_64-unknown-none" PARENT_SCOPE)
   elseif(CONFIG_ARCH_POSIX AND CONFIG_64BIT AND (${CMAKE_HOST_SYSTEM_PROCESSOR} MATCHES "aarch64"))
diff --git a/Kconfig b/Kconfig
index 0b2d057b..f84862cf 100644
--- a/Kconfig
+++ b/Kconfig
@@ -9,6 +9,7 @@ config RUST_SUPPORTED
 	bool
 	default y if ((CPU_CORTEX_M || \
 				(RISCV && !RISCV_ISA_RV32E && !RISCV_ISA_RV128I) || \
+				XTENSA || \
 				(ARCH_POSIX && 64BIT)) && \
 				!TIMER_READS_ITS_FREQUENCY_AT_RUNTIME)
 	help
diff --git a/zephyr-build/src/lib.rs b/zephyr-build/src/lib.rs
index 6fd4f772..5af2be14 100644
--- a/zephyr-build/src/lib.rs
+++ b/zephyr-build/src/lib.rs
@@ -78,7 +78,11 @@ pub fn build_kconfig_mod() {
         let line = line.expect("reading line from dotconfig");
         if let Some(caps) = config_hex.captures(&line) {
             writeln!(&mut f, "#[allow(dead_code)]").unwrap();
-            writeln!(&mut f, "pub const {}: usize = {};", &caps[1], &caps[2]).unwrap();
+            // Hex values wider than 32 bits (e.g. ESP32-S3 GPIO masks) don't
+            // fit usize on 32-bit targets; widen the type to match the value.
+            let value = u64::from_str_radix(&caps[2][2..], 16).unwrap_or(u64::MAX);
+            let ty = if value > u32::MAX as u64 { "u64" } else { "usize" };
+            writeln!(&mut f, "pub const {}: {} = {};", &caps[1], ty, &caps[2]).unwrap();
         } else if let Some(caps) = config_int.captures(&line) {
             writeln!(&mut f, "#[allow(dead_code)]").unwrap();
             writeln!(&mut f, "pub const {}: isize = {};", &caps[1], &caps[2]).unwrap();