bios_hello_world_c

bios_hello_world_c/README.adoc

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+TODO not working.
+
+A single stage educational minimal C BIOS hello world example for: https://stackoverflow.com/questions/22054578/how-to-run-a-program-without-an-operating-system/32483545#32483545

bios_hello_world_c/build.sh

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+#!/usr/bin/env bash
+set -eux
+as -ggdb3 -o entry.o entry.S
+gcc -c -ggdb3 -nostartfiles -nostdlib -o main.o main.c
+ld                  -o main.elf -T linker.ld entry.o main.o
+ld --oformat binary -o main.img -T linker.ld entry.o main.o
+qemu-system-x86_64 -hda main.img

bios_hello_world_c/entry.S

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+.text
+.global mystart
+mystart:
+    mov %rsp, __stack_top
+    call main
+    jmp .

bios_hello_world_c/linker.ld

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+ENTRY(mystart)
+SECTIONS
+{
+  .text : {
+    entry.o(.text)
+    *(.text)
+    *(.rodata)
+    *(.data)
+    /**(.eh_frame)*/
+    . = 0x1FE;
+    SHORT(0xAA55)
+  }
+  /* Reserve 16 MiB of stack. */
+  __stack_bottom = .;
+  . = . + 0x1000000;
+  __stack_top = .;
+}

bios_hello_world_c/main.c

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+void main(void) {
+    while (1);
+}