feat(run): initial run script

.clang-format

@@ -0,0 +1,8 @@
+BasedOnStyle: LLVM
+UseTab: Always
+TabWidth: 4
+IndentWidth: 4
+IndentCaseLabels: true
+ColumnLimit: 120
+PointerAlignment: Right
+AllowShortFunctionsOnASingleLine: None

.clangd

@@ -0,0 +1,2 @@
+Completion:
+  HeaderInsertion: Never

.gitignore

@@ -1,3 +1,13 @@
+/disk/*
+!/disk/.gitkeep
+*.map
+*.tar
+*.o
+*.elf
+*.bin
+*.log
+*.pcap
+
 # ---> C
 # Prerequisites
 *.d
@@ -51,4 +61,3 @@ modules.order
 Module.symvers
 Mkfile.old
 dkms.conf
-

README.md

@@ -1,2 +1,3 @@
 # rivos
 
+This toy os is made following the [OS in 1,000 lines](https://1000os.seiya.me/en/) project.

kernel.ld

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+/*
+ * This is the entry point
+ * `boot` should be a defined label
+ */
+ENTRY(boot)
+
+/* SECTIONS tells to linker how to arrange sections inside the memory */
+SECTIONS {
+    /*
+     * This is the base address (start address of the kernel)
+     * OpenSBI takes little ram
+     */
+    . = 0x80200000;
+
+    /* This section contains the code of the program */
+    .text :{
+        /*
+         * Take the .text.boot before everything
+         * KEEP() prevents the linker to mark it as "unused"
+         */
+        KEEP(*(.text.boot));
+        /* Include everything else inside the .text section */
+        *(.text .text.*);
+    }
+
+    /*
+     * Contains constant read-only data
+     * Align the start of the section at 4 byte
+     */
+    .rodata : ALIGN(4) {
+        *(.rodata .rodata.*);
+    }
+
+    /* Contains read/write data */
+    .data : ALIGN(4) {
+        *(.data .data.*);
+    }
+
+    /* Contains read/data with an initial value of zero */
+    .bss : ALIGN(4) {
+        __bss = .;
+        *(.bss .bss.* .sbss .sbss.*);
+        __bss_end = .;
+    }
+
+    . = ALIGN(4);
+    . += 128 * 1024; /* 128KB */
+    __stack_top = .;
+}

run.sh

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+#!/bin/bash
+
+# -x -> trace: print every command
+# -u -> exit if undefined variables are used
+# -e -> exit if an error occurs
+set -xue
+
+QEMU=qemu-system-riscv32
+
+# Compile
+CC=clang
+# -ffreestanding: do not use stdlib of the host environment
+# -fuse-ld=lld: LLVM linker
+# -fno-stack-protector: disable stack protection
+# -Wl,-Tkernel.ld: linker script
+# -Wl,-Map=kernel.map: output a map file (linker allocationr result)
+CFLAGS="-std=c11 -O2 -g3 -Wall -Wextra --target=riscv32-unknown-elf -fuse-ld=lld -fno-stack-protector -ffreestanding -nostdlib"
+
+$CC $CFLAGS -Wl,-Tkernel.ld -Wl,-Map=kernel.map -o kernel.elf \
+    src/kernel.c
+
+# Run QEMU
+# -machine virt: generic riscv platform
+# -bios default: load the default firmware (OpenSBI)
+# -nographic: disable VGA, everything on console
+# -serial mon:stdio: serial port is connected to terminal's stdin/stdout
+# --no-reboot: do not reboot if there's panic/shutdown/crash
+$QEMU -machine virt -bios default -nographic -serial mon:stdio --no-reboot \
+    -kernel kernel.elf
+
+# Press Ctrl+A and then C to enter QEMU debug console and quit with `q`

src/kernel.c

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+typedef unsigned char u8;
+typedef unsigned int u32;
+typedef u32 size_t;
+
+extern char __bss[], __bss_end[], __stack_top[];
+
+void *memset(void *buf, char c, size_t n) {
+	u8 *p = (u8 *)buf;
+	while (n--) {
+		*p++ = c;
+	}
+
+	return buf;
+}
+
+void kernel_main(void) {
+	memset(__bss, 0, __bss_end - __bss);
+
+	for (;;)
+		;
+}
+
+__attribute__((section(".text.boot"))) __attribute__((naked)) void boot(void) {
+	__asm__ __volatile__("mv sp, %[stack_top]\n"
+						 "j kernel_main\n"
+						 :
+						 : [stack_top] "r"(__stack_top));
+}