From 440b48df5b0da71dc8665f816e53394a21686875 Mon Sep 17 00:00:00 2001
From: rezado <1908819406@qq.com>
Date: Mon, 1 Jun 2026 15:32:52 +0800
Subject: [PATCH] fix(dts): reserve gcpt memory in FPGA templates

Add reserved-memory nodes to XiangShan FPGA DTS templates so Linux leaves the gcpt checkpoint buffer unused.

Document the gcpt reservation requirement in the Linux workloads image layout section.
---
 README.md                                    |  2 ++
 dts/xiangshan-fpga-noAIA-mem24g-novec.dts.in | 11 +++++++++++
 dts/xiangshan-fpga-noAIA-mem24g.dts.in       | 11 +++++++++++
 dts/xiangshan-fpga-noAIA-mem64g-novec.dts.in | 11 +++++++++++
 dts/xiangshan-fpga-noAIA-mem64g.dts.in       | 11 +++++++++++
 dts/xiangshan-fpga-noAIA-mem8g-novec.dts.in  | 11 +++++++++++
 dts/xiangshan-fpga-noAIA-mem8g.dts.in        | 11 +++++++++++
 dts/xiangshan-fpga-noAIA-novec.dts.in        | 11 +++++++++++
 dts/xiangshan-fpga-noAIA.dts.in              | 11 +++++++++++
 9 files changed, 90 insertions(+)

diff --git a/README.md b/README.md
index 1f42f6a..f3aef2b 100644
--- a/README.md
+++ b/README.md
@@ -57,6 +57,8 @@ For Linux workloads, the image assumes that execution begins at `0x80000000`, an
 
 Multiple device trees are built for each workload, each corresponds to a specific NEMU configuration. The device tree files are placed under the `dt` directory in the build output directory of that workload. The "default" device tree built into the image is `dt/xiangshan.dtb`. To replace the device tree, the following command can be used:
 
+For DTS files used with gcpt, the beginning of RAM must be reserved with a `reserved-memory` node so Linux does not allocate or map the gcpt checkpoint buffer. The XiangShan FPGA DTS templates reserve 1 MiB at `0x80000000` for this purpose.
+
 ```shell
 dd conv=notrunc bs=1024 seek=1536 if=dt/some_device.dtb of=fw_payload.bin
 ```
diff --git a/dts/xiangshan-fpga-noAIA-mem24g-novec.dts.in b/dts/xiangshan-fpga-noAIA-mem24g-novec.dts.in
index 861ad1b..74c2f57 100644
--- a/dts/xiangshan-fpga-noAIA-mem24g-novec.dts.in
+++ b/dts/xiangshan-fpga-noAIA-mem24g-novec.dts.in
@@ -93,6 +93,17 @@
 		reg = <0x0 0x80000000 0x6 0x00000000>;
 	};
 
+	reserved-memory {
+		#address-cells = <2>;
+		#size-cells = <2>;
+		ranges;
+
+		reserved0: buffer@0 {
+			no-map;
+			reg = <0x0 0x80000000 0x0 0x100000>;
+		};
+	};
+
 	soc {
 		#address-cells = <2>;
 		#size-cells = <2>;
diff --git a/dts/xiangshan-fpga-noAIA-mem24g.dts.in b/dts/xiangshan-fpga-noAIA-mem24g.dts.in
index df47ca2..57f61c2 100644
--- a/dts/xiangshan-fpga-noAIA-mem24g.dts.in
+++ b/dts/xiangshan-fpga-noAIA-mem24g.dts.in
@@ -94,6 +94,17 @@
 		reg = <0x0 0x80000000 0x6 0x00000000>;
 	};
 
+	reserved-memory {
+		#address-cells = <2>;
+		#size-cells = <2>;
+		ranges;
+
+		reserved0: buffer@0 {
+			no-map;
+			reg = <0x0 0x80000000 0x0 0x100000>;
+		};
+	};
+
 	soc {
 		#address-cells = <2>;
 		#size-cells = <2>;
diff --git a/dts/xiangshan-fpga-noAIA-mem64g-novec.dts.in b/dts/xiangshan-fpga-noAIA-mem64g-novec.dts.in
index f0cc705..7e2eb26 100644
--- a/dts/xiangshan-fpga-noAIA-mem64g-novec.dts.in
+++ b/dts/xiangshan-fpga-noAIA-mem64g-novec.dts.in
@@ -93,6 +93,17 @@
 		reg = <0x0 0x80000000 0x10 0x00000000>;
 	};
 
+	reserved-memory {
+		#address-cells = <2>;
+		#size-cells = <2>;
+		ranges;
+
+		reserved0: buffer@0 {
+			no-map;
+			reg = <0x0 0x80000000 0x0 0x100000>;
+		};
+	};
+
 	soc {
 		#address-cells = <2>;
 		#size-cells = <2>;
diff --git a/dts/xiangshan-fpga-noAIA-mem64g.dts.in b/dts/xiangshan-fpga-noAIA-mem64g.dts.in
index 5236aec..350b118 100644
--- a/dts/xiangshan-fpga-noAIA-mem64g.dts.in
+++ b/dts/xiangshan-fpga-noAIA-mem64g.dts.in
@@ -94,6 +94,17 @@
 		reg = <0x0 0x80000000 0x10 0x00000000>;
 	};
 
+	reserved-memory {
+		#address-cells = <2>;
+		#size-cells = <2>;
+		ranges;
+
+		reserved0: buffer@0 {
+			no-map;
+			reg = <0x0 0x80000000 0x0 0x100000>;
+		};
+	};
+
 	soc {
 		#address-cells = <2>;
 		#size-cells = <2>;
diff --git a/dts/xiangshan-fpga-noAIA-mem8g-novec.dts.in b/dts/xiangshan-fpga-noAIA-mem8g-novec.dts.in
index 12e110a..dd51c7a 100644
--- a/dts/xiangshan-fpga-noAIA-mem8g-novec.dts.in
+++ b/dts/xiangshan-fpga-noAIA-mem8g-novec.dts.in
@@ -94,6 +94,17 @@
 		reg = <0x0 0x80000000 0x2 0x00000000>;
 	};
 
+	reserved-memory {
+		#address-cells = <2>;
+		#size-cells = <2>;
+		ranges;
+
+		reserved0: buffer@0 {
+			no-map;
+			reg = <0x0 0x80000000 0x0 0x100000>;
+		};
+	};
+
 	soc {
 		#address-cells = <2>;
 		#size-cells = <2>;
diff --git a/dts/xiangshan-fpga-noAIA-mem8g.dts.in b/dts/xiangshan-fpga-noAIA-mem8g.dts.in
index 1b172ea..b0f7fd1 100644
--- a/dts/xiangshan-fpga-noAIA-mem8g.dts.in
+++ b/dts/xiangshan-fpga-noAIA-mem8g.dts.in
@@ -95,6 +95,17 @@
 		reg = <0x0 0x80000000 0x2 0x00000000>;
 	};
 
+	reserved-memory {
+		#address-cells = <2>;
+		#size-cells = <2>;
+		ranges;
+
+		reserved0: buffer@0 {
+			no-map;
+			reg = <0x0 0x80000000 0x0 0x100000>;
+		};
+	};
+
 	soc {
 		#address-cells = <2>;
 		#size-cells = <2>;
diff --git a/dts/xiangshan-fpga-noAIA-novec.dts.in b/dts/xiangshan-fpga-noAIA-novec.dts.in
index fc6ecf8..8af193d 100644
--- a/dts/xiangshan-fpga-noAIA-novec.dts.in
+++ b/dts/xiangshan-fpga-noAIA-novec.dts.in
@@ -94,6 +94,17 @@
 		reg = <0x0 0x80000000 0x0 0x80000000>;
 	};
 
+	reserved-memory {
+		#address-cells = <2>;
+		#size-cells = <2>;
+		ranges;
+
+		reserved0: buffer@0 {
+			no-map;
+			reg = <0x0 0x80000000 0x0 0x100000>;
+		};
+	};
+
 	soc {
 		#address-cells = <2>;
 		#size-cells = <2>;
diff --git a/dts/xiangshan-fpga-noAIA.dts.in b/dts/xiangshan-fpga-noAIA.dts.in
index abe653a..99d9661 100644
--- a/dts/xiangshan-fpga-noAIA.dts.in
+++ b/dts/xiangshan-fpga-noAIA.dts.in
@@ -95,6 +95,17 @@
 		reg = <0x0 0x80000000 0x0 0x80000000>;
 	};
 
+	reserved-memory {
+		#address-cells = <2>;
+		#size-cells = <2>;
+		ranges;
+
+		reserved0: buffer@0 {
+			no-map;
+			reg = <0x0 0x80000000 0x0 0x100000>;
+		};
+	};
+
 	soc {
 		#address-cells = <2>;
 		#size-cells = <2>;