feat(boom): add the 2 GiB FPGA DTS and gcc16 Zba/Zbb/Zbs SPEC2006 config

Makefile

@@ -47,8 +47,8 @@ endif
 # from it through the print-buildroot-version target, so a bump here is enough.
 BUILDROOT_VERSION := 2026.08
 BUILDROOT_DIR := build/buildroot
-# DEFAULT_DTB=nutshell or nutshell-* -> nutshell_defconfig; otherwise xiangshan_defconfig.
-BUILDROOT_DEFCONFIG := $(if $(filter nutshell nutshell-%,$(DEFAULT_DTB)),nutshell_defconfig,xiangshan_defconfig)
+# Select a matching userspace, kernel, and workload-launch protocol.
+BUILDROOT_DEFCONFIG := $(if $(filter boom-mem2g boom-fpga-mem2g,$(DEFAULT_DTB)),boom_defconfig,$(if $(filter nutshell nutshell-%,$(DEFAULT_DTB)),nutshell_defconfig,xiangshan_defconfig))
 BUILDROOT_CONFIG_STAMP := build/buildroot-config/$(BUILDROOT_DEFCONFIG)
 $(BUILDROOT_DIR)/Makefile:
 	mkdir -p build
@@ -68,12 +68,13 @@ $(BUILDROOT_CONFIG_STAMP): br2-external/configs/$(BUILDROOT_DEFCONFIG) $(BUILDRO
 TOOLCHAIN_WRAPPER := $(BUILDROOT_DIR)/output/host/bin/toolchain-wrapper
 $(TOOLCHAIN_WRAPPER): $(BUILDROOT_CONFIG_STAMP)
 	$(MAKE) -C $(BUILDROOT_DIR) BR2_EXTERNAL=$(abspath br2-external) $(BUILDROOT_DEFCONFIG)
+	$(MAKE) -C $(BUILDROOT_DIR) BR2_EXTERNAL=$(abspath br2-external) nemu-exec-dirclean
 	$(MAKE) -C $(BUILDROOT_DIR) BR2_EXTERNAL=$(abspath br2-external) prepare-sdk
 	touch $(TOOLCHAIN_WRAPPER)
 
 # Build Linux kernel
 LINUX_IMAGE := $(BUILDROOT_DIR)/output/images/Image
-$(LINUX_IMAGE): $(TOOLCHAIN_WRAPPER) $(BUILDROOT_CONFIG_STAMP) br2-external/board/openxiangshan/nemu/linux.config $(if $(filter nutshell_defconfig,$(BUILDROOT_DEFCONFIG)),br2-external/board/openxiangshan/nemu/linux-nutshell.fragment)
+$(LINUX_IMAGE): $(TOOLCHAIN_WRAPPER) $(BUILDROOT_CONFIG_STAMP) br2-external/board/openxiangshan/nemu/linux.config $(if $(filter nutshell_defconfig,$(BUILDROOT_DEFCONFIG)),br2-external/board/openxiangshan/nemu/linux-nutshell.fragment) $(if $(filter boom_defconfig,$(BUILDROOT_DEFCONFIG)),br2-external/board/openxiangshan/nemu/linux-boom.fragment)
 	$(MAKE) -C $(BUILDROOT_DIR) BR2_EXTERNAL=$(abspath br2-external) $(BUILDROOT_DEFCONFIG)
 	$(MAKE) -C $(BUILDROOT_DIR) BR2_EXTERNAL=$(abspath br2-external)
 

README.md

@@ -131,6 +131,30 @@ See the
 [SPEC2006 configuration](workloads/linux/spec2006/README.md#configuration)
 section for `riscv_gcc16_rv64imac_lp64.cfg`.
 
+## BOOM FPGA profile
+
+Use `DEFAULT_DTB=boom-mem2g` for the single-hart 2 GiB BOOM board:
+
+```sh
+make linux/coremark DEFAULT_DTB=boom-mem2g
+make linux/spec2006 BENCH=mcf INPUT=ref DEFAULT_DTB=boom-mem2g \
+  SPEC2006_CFG=workloads/linux/spec2006/configs/gcc16-linux-riscv64-rv64gc_zba_zbb_zbs.cfg \
+  SPEC2006_ISO=/path/to/cpu2006.iso
+```
+
+This selects `boom_defconfig`: RV64GC userspace, a kernel without V/H,
+no startup profiling traps, and the existing BOOM DTS with
+`rv64gc_zba_zbb_zbs`. SPEC2006 also selects the shown cfg by default for this
+DTS. Set the SPEC compiler and jemalloc inputs as described in its README.
+GCPT, OpenSBI, the kernel and initramfs use the existing firmware flow and
+DTS-derived addresses; no private boot stub or PMP/time workaround is applied.
+This is a build profile, not evidence of a completed Linux or board run.
+
+`BR2_PACKAGE_NEMU_EXEC_PROFILE` defaults to enabled for existing profiles.
+BOOM disables only the two startup traps; the final raw `waitpid` status is
+preserved (`exit 1` reports `0x100`). Run `python3 scripts/test-nemu-exec.py`
+for a native launcher regression that replaces only the hardware trap.
+
 ## Build Requirements
 
 Any modern Linux distributions should be okay. The build system of this project is using the toolchain provided by buildroot, so you do not have to set up the toolchains manually to build most workloads. Some workloads require additional toolchians not provided by buildroot. Please refer to the README file of each workload (`README.md` in the workload directory) for details.

br2-external/board/openxiangshan/nemu/linux-boom.fragment

@@ -0,0 +1,4 @@
+# BOOM implements RV64GC with Zba/Zbb/Zbs, without V or H.
+# CONFIG_RISCV_ISA_V is not set
+# CONFIG_VIRTUALIZATION is not set
+# CONFIG_KVM is not set

br2-external/configs/boom_defconfig

@@ -0,0 +1,16 @@
+# BOOM RV64GC, 2 GiB, single hart. Bootlin rv64gc toolchain.
+BR2_riscv=y
+BR2_RISCV_ISA_RVC=y
+BR2_TOOLCHAIN_EXTERNAL=y
+BR2_TARGET_GENERIC_HOSTNAME="boom"
+BR2_TARGET_GENERIC_ISSUE="BOOM FPGA Test Image"
+BR2_TARGET_GENERIC_ROOT_PASSWD="xiangshan"
+BR2_LINUX_KERNEL=y
+BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
+BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="${BR2_EXTERNAL}/board/openxiangshan/nemu/linux.config"
+BR2_LINUX_KERNEL_CONFIG_FRAGMENT_FILES="${BR2_EXTERNAL}/board/openxiangshan/nemu/linux-boom.fragment"
+BR2_TARGET_ROOTFS_INITRAMFS=y
+BR2_PACKAGE_BUSYBOX_CONFIG_FRAGMENT_FILES="${BR2_EXTERNAL}/board/openxiangshan/nemu/busybox-taskset.fragment"
+BR2_PACKAGE_NEMU_TRAP=y
+BR2_PACKAGE_NEMU_EXEC=y
+# BR2_PACKAGE_NEMU_EXEC_PROFILE is not set

br2-external/package/nemu-exec/Config.in

@@ -5,3 +5,12 @@ config BR2_PACKAGE_NEMU_EXEC
 	  NEMU workload shim.
 
 	  https://github.com/scratch-er/nemu-workloads
+
+config BR2_PACKAGE_NEMU_EXEC_PROFILE
+	bool "emit startup profiling markers"
+	depends on BR2_PACKAGE_NEMU_EXEC
+	default y
+	help
+	  Emit trap codes 0x100 and 0x101 before starting the workload.
+	  Disable on BOOM, where every trap terminates the simulation.
+	  The final waitpid status is always reported, including 0x100.

br2-external/package/nemu-exec/main.c

@@ -1,6 +1,10 @@
 #include <unistd.h>
 #include <sys/wait.h>
 
+#ifndef NEMU_EXEC_PROFILE
+#define NEMU_EXEC_PROFILE 1
+#endif
+
 #define DISABLE_TIME_INTR 0x100
 #define NOTIFY_PROFILER 0x101
 #define GOOD_TRAP 0
@@ -21,8 +25,10 @@ int main(int argc, char *argv[]) {
         trap(BAD_TRAP);
     } else if (pid == 0) {
         // child process, enable profiling and run workload
-        trap(DISABLE_TIME_INTR);
-        trap(NOTIFY_PROFILER);
+        if (NEMU_EXEC_PROFILE) {
+            trap(DISABLE_TIME_INTR);
+            trap(NOTIFY_PROFILER);
+        }
         execvp(argv[1], argv+1);
         // should not reach here
         trap(BAD_TRAP);
@@ -40,7 +46,3 @@ int main(int argc, char *argv[]) {
     // should not reach here
     return 0;
 }
-
-void trap(int code) {
-    asm volatile("mv a0, %0; .word 0x0005006b" : :"r"(code));
-}

br2-external/package/nemu-exec/nemu-exec.mk

@@ -4,7 +4,7 @@ NEMU_EXEC_SITE_METHOD = local
 NEMU_EXEC_INSTALL_STAGING = NO
 
 define NEMU_EXEC_BUILD_CMDS
-	$(TARGET_CC) $(TARGET_CFLAGS) $(@D)/main.c -o $(@D)/nemu-exec
+	$(TARGET_CC) $(TARGET_CFLAGS) -DNEMU_EXEC_PROFILE=$(if $(BR2_PACKAGE_NEMU_EXEC_PROFILE),1,0) $(@D)/main.c $(@D)/trap.c -o $(@D)/nemu-exec
 endef
 
 define NEMU_EXEC_INSTALL_TARGET_CMDS

br2-external/package/nemu-exec/trap.c

@@ -0,0 +1,3 @@
+void trap(int code) {
+    asm volatile("mv a0, %0; .word 0x0005006b" : : "r"(code) : "a0", "memory");
+}

dts/generate-nemu-board-dts.py

@@ -50,6 +50,8 @@ def parse_name(name):
         "spike-2core": (2, 2 << 30),
         "yanqihu": (1, 128 << 20),
         "yanqihu-2core": (2, 128 << 20),
+        "boom-mem2g": (1, 2 << 30),
+        "boom-fpga-mem2g": (1, 2 << 30),
         "xiangshan-fpga-AIA-mem16g": (1, 16 << 30),
     }
     if name in fixed:
@@ -99,15 +101,26 @@ def cache_properties(nemu=False, timebase=False):
     return "\n".join(result)
 
 
-def serial16550():
-    return """uart0: serial@310b0000 {
+def serial16550(label="uart0"):
+    return f"""{label}: serial@310b0000 {{
     compatible = "ns16550a";
     reg = <0x0 0x310b0000 0x0 0x10000>;
     reg-shift = <2>;
     reg-io-width = <4>;
     clock-frequency = <50000000>;
     current-speed = <115200>;
     status = "okay";
+}};"""
+
+
+def serial_boom():
+    return """serial0: ns16550@10000000 {
+    compatible = "ns16550a";
+    clock-frequency = <10000000>;
+    reg = <0x0 0x10000000 0x0 0x100>;
+    reg-shift = <0>;
+    reg-io-width = <1>;
+    status = "okay";
 };"""
 
 
@@ -377,6 +390,46 @@ def render(name, isa_config_name=None):
                      reserved_memories=[], plic_machine_first=False,
                      chosen_properties=chosen_properties("nemu"),
                      bootargs="console=hvc0 earlycon=sbi")
+    elif name == "boom-mem2g":
+        gen = DTSGen(
+            compatible="freechips,rocketchip-unknown",
+            model="freechips,rocketchip-unknown",
+            cpu_compatibles=["riscv"],
+            isa_extensions=DTSGen.sort_isa_extensions(
+                "i m a f d c zicsr zifencei zba zbb zbs".split()),
+            legacy_isa="rv64imafdc_zba_zbb_zbs",
+            mmu_type="riscv,sv39",
+            timebase_freq=1000000,
+            nr_harts=1,
+            clint_addr=0x02000000,
+            plic_addr=0x0c000000,
+            plic_ndev=31,
+            memories=[(DRAM_BASE, 2 << 30)],
+            reserved_memories=[],
+            uartlite_addr=None,
+            chosen_properties=chosen_properties("spike"),
+            bootargs="console=ttyS0,115200 earlycon=uart8250,mmio,0x10000000")
+        gen.add_device(serial_boom())
+    elif name == "boom-fpga-mem2g":
+        gen = DTSGen(
+            compatible="freechips,rocketchip-unknown",
+            model="freechips,rocketchip-unknown",
+            cpu_compatibles=["riscv"],
+            isa_extensions=DTSGen.sort_isa_extensions(
+                "i m a f d c zicsr zifencei zba zbb zbs".split()),
+            legacy_isa="rv64imafdc_zba_zbb_zbs",
+            mmu_type="riscv,sv39",
+            timebase_freq=1000000,
+            nr_harts=1,
+            clint_addr=0x02000000,
+            plic_addr=0x0c000000,
+            plic_ndev=31,
+            memories=[(DRAM_BASE, 2 << 30)],
+            reserved_memories=[],
+            uartlite_addr=None,
+            chosen_properties=chosen_properties("spike"),
+            bootargs="console=ttyS0,115200 earlycon=uart8250,mmio32,0x310b0000")
+        gen.add_device(serial16550("serial0"))
     elif name.startswith("spike"):
         nr_harts = 2 if name == "spike-2core" else 1
         gen = DTSGen(compatible="ucbbar,spike-bare-dev", model="ucbbar,spike-bare",

scripts/test-nemu-exec.py

@@ -0,0 +1,48 @@
+#!/usr/bin/env python3
+"""Run the real fork/exec/wait launcher, replacing only the RISC-V trap."""
+import os
+from pathlib import Path
+import subprocess
+import tempfile
+
+ROOT = Path(__file__).resolve().parents[1]
+TRAP = r'''#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+static pid_t parent;
+__attribute__((constructor)) static void init(void) { parent = getpid(); }
+void trap(int code) {
+    FILE *log = fopen(getenv("TRAP_LOG"), "a");
+    if (!log) _exit(99);
+    fprintf(log, "trap:%d\n", code);
+    fclose(log);
+    if (getpid() == parent) _exit(0);
+    if (code == -1) _exit(1);
+}
+'''
+
+with tempfile.TemporaryDirectory() as tmp:
+    tmp = Path(tmp)
+    (tmp / "trap.c").write_text(TRAP)
+    for profile in (0, 1):
+        exe = tmp / f"nemu-exec-{profile}"
+        subprocess.run([os.environ.get("CC", "cc"), "-Wall", "-Wextra", "-Werror",
+                        f"-DNEMU_EXEC_PROFILE={profile}",
+                        str(ROOT / "br2-external/package/nemu-exec/main.c"),
+                        str(tmp / "trap.c"), "-o", str(exe)], check=True)
+        for status in (0, 1):
+            log = tmp / "events"
+            log.write_text("")
+            env = dict(os.environ, TRAP_LOG=str(log))
+            subprocess.run([str(exe), "/bin/sh", "-c",
+                            f'printf "workload\\n" >> "$TRAP_LOG"; exit {status}'],
+                           env=env, check=True, timeout=5)
+            expected = (["trap:256", "trap:257"] if profile else [])
+            expected += ["workload", f"trap:{status << 8}"]
+            assert log.read_text().splitlines() == expected, log.read_text()
+        for command in ([], ["/this-command-does-not-exist"]):
+            log.write_text("")
+            subprocess.run([str(exe), *command], env=env, check=True, timeout=5)
+            events = log.read_text().splitlines()
+            assert "trap:-1" in events, events
+    print("PASS: profiling enabled/disabled, actual exec, exit 0/1, missing command")