Migrated first 6 gists.

kernel.c/Makefile

@@ -0,0 +1,12 @@
+.PHONY: all
+all: kernel-1989
+	qemu-system-i386 -kernel kernel-1989 -d guest_errors
+
+kernel-1989: boot.s kmain.c
+	gcc -m32 -c boot.s -o boot.o
+	gcc -m32 -std=c99 -c kmain.c -o kmain.o
+	ld -m elf_i386 -T link.ld -o kernel-1989 boot.o kmain.o
+
+.PHONY: clean
+clean:
+	rm -f *.o kernel-1989

kernel.c/README.md

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+Hello, Kernel! - An absolutely minimal barebones x86 OS kernel, based on this tutorial https://arjunsreedharan.org/post/82710718100/kernel-101-lets-write-a-kernel
+

kernel.c/kernel.c

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+#include <stdint.h>
+#include <stdbool.h>
+
+void kmain(void) {
+  const char * str = "Hello, Kernel!";
+  const char colors[16] = { 0x00, 0x01, 0x02, 0x03,
+			    0x04, 0x05, 0x06, 0x07,
+			    0x08, 0x09, 0x0A, 0x0B,
+			    0x0C, 0x0D, 0x0E, 0x0F
+  };
+  char * vidptr = (char *)0xB8000;
+  uint32_t i = 0;
+  uint32_t j = 0;
+  uint32_t k = 0;
+  uint32_t l = 0;
+
+  while (true) {
+    while (j < 80 * 25 * 2) {
+      vidptr[j] = ' ';
+      vidptr[j + 1] = 0x00;
+      j = j + 2;
+    }
+
+    k = 0;
+    i = 0;
+    while (k < 80 * 25) {
+      j = 0;
+      while (str[j]) {
+	vidptr[i] = str[j];
+	vidptr[i + 1] = colors[l];
+	j++;
+	i += 2;
+	l = (l + 1) % 16;
+      }
+      vidptr[i] = ' ';
+      vidptr[i + 1] = colors[l];
+      i += 2;
+      k += 14;
+    }
+
+    k = 0;
+    while (k < 1500000)
+      k++;
+  }
+
+  return;
+}

kernel.c/kernel.s

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+	.section .text
+
+	// Multiboot header
+	.align 4
+	.long 0x1BADB002
+	.long 0x00
+	.long -0x1BADB002
+
+	// Entry point
+	.globl start
+
+start:
+	cli
+	mov $stack_top, %esp
+	call kmain
+	hlt
+
+	.section .bss
+	
+	.comm stack_bottom, 8192, 4
+stack_top:

kernel.c/link.ld

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+OUTPUT_FORMAT(elf32-i386)
+ENTRY(start)
+SECTIONS
+ {
+    . = 0x100000;
+    .text : { *(.text) }
+    .data : { *(.data) }
+    .bss  : { *(.bss)  }
+ }