Added a very basic types.h header file that defines NULL, size_t and

time_t.
Moved the kernel's loading point down to address 0 in
conventional memory and updated linker scripts accordingly.
Began to experiment with loading a binary blob into extended memory
(0x100000), switching to userspace mode, and executing it.

3 files changed, 49 insertions, 0 deletions

diff --git a/kernel/usrbin/Makefile b/kernel/usrbin/Makefile
new file mode 100644
index 0000000..dfd1b84
--- /dev/null
+++ b/kernel/usrbin/Makefile
@@ -0,0 +1,17 @@
+TARGET = usrbin.o
+
+ASM = nasm
+
+all: build
+
+build: $(TARGET)
+
+usrbin.bin: usrbin.s
+	$(ASM) -f bin -o usrbin.bin usrbin.s
+
+$(TARGET): usrbin.bin
+	objcopy -I binary -O elf32-i386 -B i386 usrbin.bin usrbin.o
+
+clean:
+	rm -f usrbin.bin
+	rm -f $(TARGET)
diff --git a/kernel/usrbin/usrbin.bin b/kernel/usrbin/usrbin.bin
new file mode 100644
index 0000000..a7d7730
--- /dev/null
+++ b/kernel/usrbin/usrbin.bin
diff --git a/kernel/usrbin/usrbin.s b/kernel/usrbin/usrbin.s
new file mode 100644
index 0000000..91dd94a
--- /dev/null
+++ b/kernel/usrbin/usrbin.s
@@ -0,0 +1,32 @@
+bits 32
+org 0x100000
+
+main:
+  push .msg
+  call puts
+  add esp, 4
+.loop:
+  ; loop forever
+  jmp .loop
+.msg: db "Hello World from Userspace!", 0
+
+puts:
+  push ebp
+  mov ebp, esp
+  push esi
+  push edi
+  mov esi, [ebp+8]
+  mov edi, 0xB8000
+.loop:
+  lodsb
+  cmp al, 0
+  je .end
+  mov [edi], al
+  mov byte [edi+1], 0x07
+  add edi, 2
+  jmp .loop
+.end:
+  pop edi
+  pop esi
+  pop ebp
+  ret