[WIP] Build OpenSBI

flake.nix

@@ -80,6 +80,7 @@
         verilator
         srecord
         d2
+        dtc
       ];
     in {
       formatter = pkgs.alejandra;

sw/CMakeLists.txt

@@ -15,4 +15,8 @@ enable_testing()
 
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
+include(ExternalProject)
+
+include(cmake/opensbi.cmake)
+
 add_subdirectory(device)

sw/cheri_toolchain.cmake

@@ -46,7 +46,11 @@ string(CONCAT CMAKE_C_FLAGS_INIT
   " -Wall -Wextra"
 )
 
-set(CMAKE_ASM_FLAGS_INIT "")
+set(CMAKE_ASM_FLAGS_INIT
+    # Workaround: Our current build of the LLVM toolchain crashes
+    # when trying to erroneously relax the devicetree assembly file.
+    "-mno-relax"
+)
 
 set(CMAKE_EXE_LINKER_FLAGS_INIT
     "-nodefaultlibs"

sw/cmake/opensbi.cmake

@@ -0,0 +1,57 @@
+# Copyright lowRISC contributors.
+# Licensed under the Apache License, Version 2.0, see LICENSE for details.
+# SPDX-License-Identifier: Apache-2.0
+
+set(OPENSBI_REPOSITORY https://github.com/lowrisc/opensbi)
+set(OPENSBI_TAG mocha-devel)
+
+# build command - run make with build options.
+set(BUILD_COMMAND
+    make
+    # Use CHERI LLVM.
+    LLVM=1
+    # ISA options.
+    PLATFORM_RISCV_XLEN=64
+    PLATFORM_RISCV_ISA=rv64imac_zcherihybrid
+    PLATFORM_RISCV_ABI=l64pc128
+    # Build for the 'generic' platform, which uses devicetree data.
+    PLATFORM=generic
+    # Use the Mocha defconfig file.
+    PLATFORM_DEFCONFIG=mocha_defconfig
+    # Build a 'payload' and 'jump' firmware.
+    FW_PAYLOAD=y
+    FW_JUMP=y
+    # Disable position-independent code and link to DRAM base,
+    # as loading position-independent executables is not supported by
+    # our Verilator ELF loader.
+    FW_PIC=n
+    FW_TEXT_START=0x80000000
+    # 0x2 bit = build with runtime debug printing.
+    FW_OPTIONS=0x2
+)
+
+# Built firmware binaries to copy into the root of the external project directory.
+set(FIRMWARES
+    build/platform/generic/firmware/fw_payload.elf
+    build/platform/generic/firmware/fw_payload.bin
+    build/platform/generic/firmware/fw_jump.elf
+    build/platform/generic/firmware/fw_jump.bin
+)
+
+# install command - copy the firmware binaries to the root of the external project directory.
+set(INSTALL_COMMAND
+    cp ${FIRMWARES} <INSTALL_DIR>
+)
+
+ExternalProject_Add(
+    opensbi PREFIX opensbi
+    GIT_REPOSITORY ${OPENSBI_REPOSITORY}
+    GIT_TAG ${OPENSBI_TAG}
+    # OpenSBI builds in its own 'build' sub-directory.
+    BUILD_IN_SOURCE true
+    # make is job server aware.
+    BUILD_JOB_SERVER_AWARE true
+    CONFIGURE_COMMAND "" # no configure step needed, do nothing here.
+    BUILD_COMMAND ${BUILD_COMMAND}
+    INSTALL_COMMAND ${INSTALL_COMMAND}
+)

sw/device/bootrom/CMakeLists.txt

@@ -6,7 +6,20 @@ set(NAME bootrom)
 add_executable(${NAME} bootrom.c)
 target_link_libraries(${NAME} hal_vanilla runtime_vanilla startup_vanilla)
 target_compile_options(${NAME} PUBLIC ${VANILLA_FLAGS})
-target_link_options(${NAME} PUBLIC 
+target_link_options(${NAME} PUBLIC
+  "-nodefaultlibs"
+  "-Wl,--defsym,BOOT_ROM_OFFSET=0x00"
+  "-T${LDS}"
+  "-L${LDS_DIR}"
+)
+install(TARGETS ${NAME})
+mocha_add_executable_artefacts(${NAME})
+
+set(NAME dt_dram_bootrom)
+add_executable(${NAME} dt_dram_bootrom.c ../devicetree/mocha.S)
+target_link_libraries(${NAME} startup_vanilla)
+target_compile_options(${NAME} PUBLIC ${VANILLA_FLAGS})
+target_link_options(${NAME} PUBLIC
   "-nodefaultlibs"
   "-Wl,--defsym,BOOT_ROM_OFFSET=0x00"
   "-T${LDS}"

sw/device/bootrom/dt_dram_bootrom.c

@@ -0,0 +1,34 @@
+// Copyright lowRISC contributors (COSMIC project).
+// Licensed under the Apache License, Version 2.0, see LICENSE for details.
+// SPDX-License-Identifier: Apache-2.0
+
+#include "boot/trap.h"
+#include "builtin.h"
+#include "hal/mocha.h"
+#if defined(__riscv_zcherihybrid)
+#include <cheriintrin.h>
+#endif /* defined(__riscv_zcherihybrid) */
+
+// An example boot ROM fragment that jumps into DRAM with
+// the current hart ID and a pointer to devicetree blob in
+// the a0 and a1 registers respectively.
+
+/* Pointer to devicetree blob, defined in devicetree/mocha.S */
+extern char dt_blob_start[];
+
+int main(void)
+{
+    asm volatile("mv a0, zero\n" /* a0 = hart id */
+                 "mv a1, %[dtb]\n" /* a1 = pointer to devicetree blob */
+                 "jr %[dram]\n"
+                 :
+                 : [dtb] "r"(dt_blob_start), [dram] "r"(dram_base)
+                 : "a0", "a1", "memory");
+    return 0;
+}
+
+void _trap_handler(struct trap_registers *registers, struct trap_context *context)
+{
+    (void)registers;
+    (void)context;
+}

sw/device/devicetree/REUSE.toml

@@ -0,0 +1,6 @@
+version = 1
+
+[[annotations]]
+path = ["mocha.S"]
+SPDX-FileCopyrightText = "lowRISC Contributors (COSMIC project)."
+SPDX-License-Identifier = "Apache-2.0"