From 8247719b65bc6841aabe56c3b210939690e31c8f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Maciej=20=27vesim=27=20Kuli=C5=84ski?= <vesim809@pm.me>
Date: Mon, 2 Feb 2026 01:46:30 +0100
Subject: [PATCH 1/4] rp2xxx: Add scratch sections

---
 port/raspberrypi/rp2xxx/build.zig             | 29 +++++++++----------
 port/raspberrypi/rp2xxx/ld/rp2040/sections.ld | 17 ++++++++++-
 .../ld/rp2350/arm_ram_image_sections.ld       | 18 +++++++++++-
 .../rp2xxx/ld/rp2350/arm_sections.ld          | 18 +++++++++++-
 .../ld/rp2350/riscv_ram_image_sections.ld     | 18 +++++++++++-
 .../rp2xxx/ld/rp2350/riscv_sections.ld        | 18 +++++++++++-
 port/raspberrypi/rp2xxx/src/hal.zig           |  1 +
 port/raspberrypi/rp2xxx/src/hal/sections.zig  |  2 ++
 8 files changed, 100 insertions(+), 21 deletions(-)
 create mode 100644 port/raspberrypi/rp2xxx/src/hal/sections.zig

diff --git a/port/raspberrypi/rp2xxx/build.zig b/port/raspberrypi/rp2xxx/build.zig
index 581169e83..5cf808c12 100644
--- a/port/raspberrypi/rp2xxx/build.zig
+++ b/port/raspberrypi/rp2xxx/build.zig
@@ -60,8 +60,10 @@ pub fn init(dep: *std.Build.Dependency) Self {
             .name = "RP2040",
             .register_definition = .{ .svd = pico_sdk.path("src/rp2040/hardware_regs/RP2040.svd") },
             .memory_regions = &.{
-                .{ .tag = .flash, .offset = 0x10000000, .length = 2048 * 1024, .access = .rx },
-                .{ .tag = .ram, .offset = 0x20000000, .length = 256 * 1024, .access = .rwx },
+                .{ .name = "FLASH", .tag = .flash, .offset = 0x10000000, .length = 2048 * 1024, .access = .rx },
+                .{ .name = "RAM", .tag = .ram, .offset = 0x20000000, .length = 256 * 1024, .access = .rwx },
+                .{ .name = "SCRATCH_X", .tag = .ram, .offset = 0x20040000, .length = 4 * 1024, .access = .rwx },
+                .{ .name = "SCRATCH_Y", .tag = .ram, .offset = 0x20041000, .length = 4 * 1024, .access = .rwx },
             },
             .patch_files = &.{b.path("patches/rp2040.zon")},
         },
@@ -71,6 +73,13 @@ pub fn init(dep: *std.Build.Dependency) Self {
         },
     };
 
+    const chip_rp2350_memory_regions = [_]microzig.MemoryRegion{
+        .{ .name = "FLASH", .tag = .flash, .offset = 0x10000000, .length = 2048 * 1024, .access = .rx },
+        .{ .name = "RAM", .tag = .ram, .offset = 0x20000000, .length = 512 * 1024, .access = .rwx },
+        .{ .name = "SCRATCH_X", .tag = .ram, .offset = 0x20080000, .length = 4 * 1024, .access = .rwx },
+        .{ .name = "SCRATCH_Y", .tag = .ram, .offset = 0x20081000, .length = 4 * 1024, .access = .rwx },
+    };
+
     const chip_rp2350_arm: microzig.Target = .{
         .dep = dep,
         .preferred_binary_format = .{ .uf2 = .{
@@ -86,13 +95,7 @@ pub fn init(dep: *std.Build.Dependency) Self {
         .chip = .{
             .name = "RP2350",
             .register_definition = .{ .svd = pico_sdk.path("src/rp2350/hardware_regs/RP2350.svd") },
-            .memory_regions = &.{
-                .{ .tag = .flash, .offset = 0x10000000, .length = 2048 * 1024, .access = .rx },
-                .{ .tag = .ram, .offset = 0x20000000, .length = 512 * 1024, .access = .rwx },
-                // TODO: maybe these can be used for stacks
-                .{ .tag = .ram, .offset = 0x20080000, .length = 4 * 1024, .access = .rwx },
-                .{ .tag = .ram, .offset = 0x20081000, .length = 4 * 1024, .access = .rwx },
-            },
+            .memory_regions = &chip_rp2350_memory_regions,
             .patch_files = &.{b.path("patches/rp2350.zon")},
         },
         .hal = hal,
@@ -138,13 +141,7 @@ pub fn init(dep: *std.Build.Dependency) Self {
         .chip = .{
             .name = "RP2350",
             .register_definition = .{ .svd = pico_sdk.path("src/rp2350/hardware_regs/RP2350.svd") },
-            .memory_regions = &.{
-                .{ .tag = .flash, .offset = 0x10000000, .length = 2048 * 1024, .access = .rx },
-                .{ .tag = .ram, .offset = 0x20000000, .length = 512 * 1024, .access = .rwx },
-                // TODO: maybe these can be used for stacks
-                .{ .tag = .ram, .offset = 0x20080000, .length = 4 * 1024, .access = .rwx },
-                .{ .tag = .ram, .offset = 0x20081000, .length = 4 * 1024, .access = .rwx },
-            },
+            .memory_regions = &chip_rp2350_memory_regions,
             .patch_files = &.{
                 b.path("patches/rp2350.zon"),
                 b.path("patches/rp2350_hazard3.zon"),
diff --git a/port/raspberrypi/rp2xxx/ld/rp2040/sections.ld b/port/raspberrypi/rp2xxx/ld/rp2040/sections.ld
index 436f923e6..6639ec9c5 100644
--- a/port/raspberrypi/rp2xxx/ld/rp2040/sections.ld
+++ b/port/raspberrypi/rp2xxx/ld/rp2040/sections.ld
@@ -4,10 +4,25 @@ SECTIONS
     __boot2_start__ = .;
     KEEP (*(.boot2))
     __boot2_end__ = .;
-  } > flash0
+  } > FLASH
 
   ASSERT(__boot2_end__ - __boot2_start__ == 256,
     "ERROR: Pico second stage bootloader must be 256 bytes in size")
 }
 INSERT BEFORE .flash_start;
 
+SECTIONS {
+  .scratch_x : {
+      microzig_scratch_x_start = .;
+      *(.scratch_x.*)
+      . = ALIGN(4);
+      microzig_scratch_x_end = .;
+  } > SCRATCH_X AT > FLASH
+
+  .scratch_y : {
+      microzig_scratch_y_start = .;
+      *(.scratch_y.*)
+      . = ALIGN(4);
+      microzig_scratch_y_end = .;
+  } > SCRATCH_Y AT > FLASH
+}
diff --git a/port/raspberrypi/rp2xxx/ld/rp2350/arm_ram_image_sections.ld b/port/raspberrypi/rp2xxx/ld/rp2350/arm_ram_image_sections.ld
index 4513ada28..66b5aace5 100644
--- a/port/raspberrypi/rp2xxx/ld/rp2350/arm_ram_image_sections.ld
+++ b/port/raspberrypi/rp2xxx/ld/rp2350/arm_ram_image_sections.ld
@@ -4,6 +4,22 @@ SECTIONS {
     __bootmeta_start__ = .;
     KEEP(*(.bootmeta))
     __bootmeta_end__ = .;
-  } > ram0
+  } > RAM
 }
 INSERT AFTER .ram_start;
+
+SECTIONS {
+  .scratch_x : {
+      microzig_scratch_x_start = .;
+      *(.scratch_x.*)
+      . = ALIGN(4);
+      microzig_scratch_x_end = .;
+  } > SCRATCH_X AT > FLASH
+
+  .scratch_y : {
+      microzig_scratch_y_start = .;
+      *(.scratch_y.*)
+      . = ALIGN(4);
+      microzig_scratch_y_end = .;
+  } > SCRATCH_Y AT > FLASH
+}
diff --git a/port/raspberrypi/rp2xxx/ld/rp2350/arm_sections.ld b/port/raspberrypi/rp2xxx/ld/rp2350/arm_sections.ld
index 3007ad8f3..eaef93374 100644
--- a/port/raspberrypi/rp2xxx/ld/rp2350/arm_sections.ld
+++ b/port/raspberrypi/rp2xxx/ld/rp2350/arm_sections.ld
@@ -4,6 +4,22 @@ SECTIONS {
     __bootmeta_start__ = .;
     KEEP(*(.bootmeta))
     __bootmeta_end__ = .;
-  } > flash0
+  } > FLASH
 }
 INSERT AFTER .flash_start;
+
+SECTIONS {
+  .scratch_x : {
+      microzig_scratch_x_start = .;
+      *(.scratch_x.*)
+      . = ALIGN(4);
+      microzig_scratch_x_end = .;
+  } > SCRATCH_X AT > FLASH
+
+  .scratch_y : {
+      microzig_scratch_y_start = .;
+      *(.scratch_y.*)
+      . = ALIGN(4);
+      microzig_scratch_y_end = .;
+  } > SCRATCH_Y AT > FLASH
+}
diff --git a/port/raspberrypi/rp2xxx/ld/rp2350/riscv_ram_image_sections.ld b/port/raspberrypi/rp2xxx/ld/rp2350/riscv_ram_image_sections.ld
index 4513ada28..66b5aace5 100644
--- a/port/raspberrypi/rp2xxx/ld/rp2350/riscv_ram_image_sections.ld
+++ b/port/raspberrypi/rp2xxx/ld/rp2350/riscv_ram_image_sections.ld
@@ -4,6 +4,22 @@ SECTIONS {
     __bootmeta_start__ = .;
     KEEP(*(.bootmeta))
     __bootmeta_end__ = .;
-  } > ram0
+  } > RAM
 }
 INSERT AFTER .ram_start;
+
+SECTIONS {
+  .scratch_x : {
+      microzig_scratch_x_start = .;
+      *(.scratch_x.*)
+      . = ALIGN(4);
+      microzig_scratch_x_end = .;
+  } > SCRATCH_X AT > FLASH
+
+  .scratch_y : {
+      microzig_scratch_y_start = .;
+      *(.scratch_y.*)
+      . = ALIGN(4);
+      microzig_scratch_y_end = .;
+  } > SCRATCH_Y AT > FLASH
+}
diff --git a/port/raspberrypi/rp2xxx/ld/rp2350/riscv_sections.ld b/port/raspberrypi/rp2xxx/ld/rp2350/riscv_sections.ld
index 3007ad8f3..eaef93374 100644
--- a/port/raspberrypi/rp2xxx/ld/rp2350/riscv_sections.ld
+++ b/port/raspberrypi/rp2xxx/ld/rp2350/riscv_sections.ld
@@ -4,6 +4,22 @@ SECTIONS {
     __bootmeta_start__ = .;
     KEEP(*(.bootmeta))
     __bootmeta_end__ = .;
-  } > flash0
+  } > FLASH
 }
 INSERT AFTER .flash_start;
+
+SECTIONS {
+  .scratch_x : {
+      microzig_scratch_x_start = .;
+      *(.scratch_x.*)
+      . = ALIGN(4);
+      microzig_scratch_x_end = .;
+  } > SCRATCH_X AT > FLASH
+
+  .scratch_y : {
+      microzig_scratch_y_start = .;
+      *(.scratch_y.*)
+      . = ALIGN(4);
+      microzig_scratch_y_end = .;
+  } > SCRATCH_Y AT > FLASH
+}
diff --git a/port/raspberrypi/rp2xxx/src/hal.zig b/port/raspberrypi/rp2xxx/src/hal.zig
index 853cdb94d..fb2f84242 100644
--- a/port/raspberrypi/rp2xxx/src/hal.zig
+++ b/port/raspberrypi/rp2xxx/src/hal.zig
@@ -39,6 +39,7 @@ pub const time = @import("hal/time.zig");
 pub const uart = @import("hal/uart.zig");
 pub const usb = @import("hal/usb.zig");
 pub const watchdog = @import("hal/watchdog.zig");
+pub const sections = @import("hal/sections.zig");
 
 comptime {
     // HACK: tests can't access microzig. maybe there's a better way to do this.
diff --git a/port/raspberrypi/rp2xxx/src/hal/sections.zig b/port/raspberrypi/rp2xxx/src/hal/sections.zig
new file mode 100644
index 000000000..caae3d5d7
--- /dev/null
+++ b/port/raspberrypi/rp2xxx/src/hal/sections.zig
@@ -0,0 +1,2 @@
+pub const scratch_x = ".scratch_x";
+pub const scratch_y = ".scratch_y";

From 2d988ba3bfdfe124f0cb59ed3d2b3136be0de1e4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Maciej=20=27vesim=27=20Kuli=C5=84ski?= <vesim809@pm.me>
Date: Mon, 2 Feb 2026 02:27:22 +0100
Subject: [PATCH 2/4] rp2xxx: copy data to scratch sections

---
 core/src/utilities.zig                           | 16 ++++++++++++++++
 port/raspberrypi/rp2xxx/ld/rp2040/sections.ld    |  2 ++
 .../rp2xxx/ld/rp2350/arm_ram_image_sections.ld   |  2 ++
 .../raspberrypi/rp2xxx/ld/rp2350/arm_sections.ld |  2 ++
 .../rp2xxx/ld/rp2350/riscv_ram_image_sections.ld |  2 ++
 .../rp2xxx/ld/rp2350/riscv_sections.ld           |  2 ++
 port/raspberrypi/rp2xxx/src/hal.zig              |  2 ++
 7 files changed, 28 insertions(+)

diff --git a/core/src/utilities.zig b/core/src/utilities.zig
index 9bcad56bf..eec8ed3fa 100644
--- a/core/src/utilities.zig
+++ b/core/src/utilities.zig
@@ -40,6 +40,22 @@ pub inline fn initialize_system_memories(which: enum {
         @memset(bss_start[0..bss_len], 0);
     }
 
+    if (@hasDecl(microzig.hal, "extra_ram_load_sections")) {
+        inline for (microzig.hal.extra_ram_load_sections) |section_name| {
+            const section = struct {
+                const start = @extern(*anyopaque, .{ .name = std.fmt.comptimePrint("microzig_{s}_start", .{section_name}) });
+                const end = @extern(*anyopaque, .{ .name = std.fmt.comptimePrint("microzig_{s}_end", .{section_name}) });
+                const load_start = @extern(*anyopaque, .{ .name = std.fmt.comptimePrint("microzig_{s}_load_start", .{section_name}) });
+            };
+            const start: [*]u8 = @ptrCast(section.start);
+            const end: [*]u8 = @ptrCast(section.end);
+            const len = @intFromPtr(end) - @intFromPtr(start);
+            const src: [*]const u8 = @ptrCast(&section.load_start);
+
+            @memcpy(start[0..len], src[0..len]);
+        }
+    }
+
     // load .data from flash
     if (which != .bss_only) {
         const data_start: [*]u8 = @ptrCast(&sections.microzig_data_start);
diff --git a/port/raspberrypi/rp2xxx/ld/rp2040/sections.ld b/port/raspberrypi/rp2xxx/ld/rp2040/sections.ld
index 6639ec9c5..edebbc5f0 100644
--- a/port/raspberrypi/rp2xxx/ld/rp2040/sections.ld
+++ b/port/raspberrypi/rp2xxx/ld/rp2040/sections.ld
@@ -18,6 +18,7 @@ SECTIONS {
       . = ALIGN(4);
       microzig_scratch_x_end = .;
   } > SCRATCH_X AT > FLASH
+  microzig_scratch_x_load_start = LOADADDR(.scratch_x);
 
   .scratch_y : {
       microzig_scratch_y_start = .;
@@ -25,4 +26,5 @@ SECTIONS {
       . = ALIGN(4);
       microzig_scratch_y_end = .;
   } > SCRATCH_Y AT > FLASH
+  microzig_scratch_y_load_start = LOADADDR(.scratch_y);
 }
diff --git a/port/raspberrypi/rp2xxx/ld/rp2350/arm_ram_image_sections.ld b/port/raspberrypi/rp2xxx/ld/rp2350/arm_ram_image_sections.ld
index 66b5aace5..341a5bf16 100644
--- a/port/raspberrypi/rp2xxx/ld/rp2350/arm_ram_image_sections.ld
+++ b/port/raspberrypi/rp2xxx/ld/rp2350/arm_ram_image_sections.ld
@@ -15,6 +15,7 @@ SECTIONS {
       . = ALIGN(4);
       microzig_scratch_x_end = .;
   } > SCRATCH_X AT > FLASH
+  microzig_scratch_x_load_start = LOADADDR(.scratch_x);
 
   .scratch_y : {
       microzig_scratch_y_start = .;
@@ -22,4 +23,5 @@ SECTIONS {
       . = ALIGN(4);
       microzig_scratch_y_end = .;
   } > SCRATCH_Y AT > FLASH
+  microzig_scratch_y_load_start = LOADADDR(.scratch_y);
 }
diff --git a/port/raspberrypi/rp2xxx/ld/rp2350/arm_sections.ld b/port/raspberrypi/rp2xxx/ld/rp2350/arm_sections.ld
index eaef93374..e8d7fa889 100644
--- a/port/raspberrypi/rp2xxx/ld/rp2350/arm_sections.ld
+++ b/port/raspberrypi/rp2xxx/ld/rp2350/arm_sections.ld
@@ -15,6 +15,7 @@ SECTIONS {
       . = ALIGN(4);
       microzig_scratch_x_end = .;
   } > SCRATCH_X AT > FLASH
+  microzig_scratch_x_load_start = LOADADDR(.scratch_x);
 
   .scratch_y : {
       microzig_scratch_y_start = .;
@@ -22,4 +23,5 @@ SECTIONS {
       . = ALIGN(4);
       microzig_scratch_y_end = .;
   } > SCRATCH_Y AT > FLASH
+  microzig_scratch_y_load_start = LOADADDR(.scratch_y);
 }
diff --git a/port/raspberrypi/rp2xxx/ld/rp2350/riscv_ram_image_sections.ld b/port/raspberrypi/rp2xxx/ld/rp2350/riscv_ram_image_sections.ld
index 66b5aace5..341a5bf16 100644
--- a/port/raspberrypi/rp2xxx/ld/rp2350/riscv_ram_image_sections.ld
+++ b/port/raspberrypi/rp2xxx/ld/rp2350/riscv_ram_image_sections.ld
@@ -15,6 +15,7 @@ SECTIONS {
       . = ALIGN(4);
       microzig_scratch_x_end = .;
   } > SCRATCH_X AT > FLASH
+  microzig_scratch_x_load_start = LOADADDR(.scratch_x);
 
   .scratch_y : {
       microzig_scratch_y_start = .;
@@ -22,4 +23,5 @@ SECTIONS {
       . = ALIGN(4);
       microzig_scratch_y_end = .;
   } > SCRATCH_Y AT > FLASH
+  microzig_scratch_y_load_start = LOADADDR(.scratch_y);
 }
diff --git a/port/raspberrypi/rp2xxx/ld/rp2350/riscv_sections.ld b/port/raspberrypi/rp2xxx/ld/rp2350/riscv_sections.ld
index eaef93374..e8d7fa889 100644
--- a/port/raspberrypi/rp2xxx/ld/rp2350/riscv_sections.ld
+++ b/port/raspberrypi/rp2xxx/ld/rp2350/riscv_sections.ld
@@ -15,6 +15,7 @@ SECTIONS {
       . = ALIGN(4);
       microzig_scratch_x_end = .;
   } > SCRATCH_X AT > FLASH
+  microzig_scratch_x_load_start = LOADADDR(.scratch_x);
 
   .scratch_y : {
       microzig_scratch_y_start = .;
@@ -22,4 +23,5 @@ SECTIONS {
       . = ALIGN(4);
       microzig_scratch_y_end = .;
   } > SCRATCH_Y AT > FLASH
+  microzig_scratch_y_load_start = LOADADDR(.scratch_y);
 }
diff --git a/port/raspberrypi/rp2xxx/src/hal.zig b/port/raspberrypi/rp2xxx/src/hal.zig
index fb2f84242..94957f98f 100644
--- a/port/raspberrypi/rp2xxx/src/hal.zig
+++ b/port/raspberrypi/rp2xxx/src/hal.zig
@@ -145,6 +145,8 @@ pub fn get_cpu_id() u32 {
     return SIO.CPUID.read().CPUID;
 }
 
+pub const extra_ram_load_sections = .{ "scratch_x", "scratch_y" };
+
 test "hal tests" {
     _ = pio;
     _ = usb;

From e15a0c7b570e3882f0772236501e715359ebe88c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Maciej=20=27vesim=27=20Kuli=C5=84ski?= <vesim809@pm.me>
Date: Mon, 2 Feb 2026 02:33:04 +0100
Subject: [PATCH 3/4] rp2xxx: fix rp2040 flashless scratch sections

---
 port/raspberrypi/rp2xxx/build.zig               |  4 +++-
 .../rp2xxx/ld/rp2040/ram_sections.ld            | 17 +++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)
 create mode 100644 port/raspberrypi/rp2xxx/ld/rp2040/ram_sections.ld

diff --git a/port/raspberrypi/rp2xxx/build.zig b/port/raspberrypi/rp2xxx/build.zig
index 5cf808c12..00909a0bd 100644
--- a/port/raspberrypi/rp2xxx/build.zig
+++ b/port/raspberrypi/rp2xxx/build.zig
@@ -193,7 +193,9 @@ pub fn init(dep: *std.Build.Dependency) Self {
                 .pico_flashless = chip_rp2040.derive(.{
                     .ram_image = true,
                     // we can use the default generated linker script
-                    .linker_script = .{},
+                    .linker_script = .{
+                        .file = b.path("ld/rp2040/ram_sections.ld"),
+                    },
                     .entry = .{ .symbol_name = "_entry_point" },
                     .board = .{
                         .name = "RaspberryPi Pico (ram image)",
diff --git a/port/raspberrypi/rp2xxx/ld/rp2040/ram_sections.ld b/port/raspberrypi/rp2xxx/ld/rp2040/ram_sections.ld
new file mode 100644
index 000000000..344018d88
--- /dev/null
+++ b/port/raspberrypi/rp2xxx/ld/rp2040/ram_sections.ld
@@ -0,0 +1,17 @@
+SECTIONS {
+  .scratch_x : {
+      microzig_scratch_x_start = .;
+      *(.scratch_x.*)
+      . = ALIGN(4);
+      microzig_scratch_x_end = .;
+  } > SCRATCH_X AT > FLASH
+  microzig_scratch_x_load_start = LOADADDR(.scratch_x);
+
+  .scratch_y : {
+      microzig_scratch_y_start = .;
+      *(.scratch_y.*)
+      . = ALIGN(4);
+      microzig_scratch_y_end = .;
+  } > SCRATCH_Y AT > FLASH
+  microzig_scratch_y_load_start = LOADADDR(.scratch_y);
+}

From d5599bdc658ef1b367311036093bad37c3685582 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Maciej=20=27vesim=27=20Kuli=C5=84ski?= <vesim809@pm.me>
Date: Mon, 2 Feb 2026 02:40:13 +0100
Subject: [PATCH 4/4] core: fix no_hal builds

---
 core/src/utilities.zig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/core/src/utilities.zig b/core/src/utilities.zig
index eec8ed3fa..bc43c6aa5 100644
--- a/core/src/utilities.zig
+++ b/core/src/utilities.zig
@@ -40,7 +40,7 @@ pub inline fn initialize_system_memories(which: enum {
         @memset(bss_start[0..bss_len], 0);
     }
 
-    if (@hasDecl(microzig.hal, "extra_ram_load_sections")) {
+    if (microzig.hal != void and @hasDecl(microzig.hal, "extra_ram_load_sections")) {
         inline for (microzig.hal.extra_ram_load_sections) |section_name| {
             const section = struct {
                 const start = @extern(*anyopaque, .{ .name = std.fmt.comptimePrint("microzig_{s}_start", .{section_name}) });