Build images for RAM-only execution

CHANGELOG.md

@@ -6,6 +6,16 @@ Establish a 32 byte reservation at the start of ITCM where instructions are
 never placed. This reduces the total capacity of ITCM by 32 bytes on nearly
 all MCUs, except the 1180.
 
+### FlexRAM bank layouts
+
+The runtime builder lets users specify the _layout_, or assignment, of FlexRAM
+banks. This is more precise than the _count_ of banks.
+
+By default, the layout remains an implementation detail of the builder. This is
+true if you only specify the count, or if you make no choice. However, if you
+specify the layout, the builder guarantees that the FlexRAM banks will match
+that layout.
+
 ## [0.1.7] 2025-06-14
 
 Introduce `RuntimeBuilder::in_flash` for creating images that can be launched

board/Cargo.toml

@@ -40,6 +40,12 @@ imxrt1010evk = [
     "dep:rtt-target",
     "dep:panic-rtt-target",
 ]
+imxrt1010evk-ram = [
+    "imxrt-ral/imxrt1011",
+    # No FCB required.
+    "dep:rtt-target",
+    "dep:panic-rtt-target",
+]
 imxrt1170evk-cm7 = [
     "imxrt-ral/imxrt1176_cm7",
     "dep:imxrt1170evk-fcb",

board/build.rs

@@ -60,6 +60,13 @@ fn main() {
                 .heap_size_env_override("BOARD_HEAP")
                 .build()
                 .unwrap(),
+            "imxrt1010evk_ram" => {
+                imxrt_rt::RuntimeBuilder::from_ram(imxrt_rt::Family::Imxrt1010)
+                    .heap_size(1024)
+                    .build()
+                    .unwrap();
+                println!("cargo:rustc-cfg=from_ram");
+            }
             _ => continue,
         }
         break;

board/src/imxrt1010evk.rs

@@ -2,7 +2,7 @@
 
 use crate::ral;
 
-#[cfg(target_arch = "arm")]
+#[cfg(all(target_arch = "arm", not(feature = "imxrt1010evk-ram")))]
 use imxrt1010evk_fcb as _;
 #[cfg(target_arch = "arm")]
 use panic_rtt_target as _;

board/src/lib.rs

@@ -10,7 +10,7 @@ cfg_if::cfg_if! {
 
         mod teensy4;
         pub use teensy4::*;
-    } else if #[cfg(feature = "imxrt1010evk")] {
+    } else if #[cfg(any(feature = "imxrt1010evk", feature = "imxrt1010evk-ram"))] {
         mod shared { pub mod imxrt10xx; }
         use shared::imxrt10xx::prepare_pit;