From 80aad418fcf63edb184a85d470531388a18cec5a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Lov=C3=A9n?= <thomasloven@gmail.com>
Date: Fri, 16 Mar 2018 09:01:31 +0100
Subject: [PATCH] Cleanup and commenting

---
 src/kernel/cpu/cpu.c       | 3 ++-
 src/kernel/cpu/registers.S | 1 -
 src/kernel/include/cpu.h   | 3 +++
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/kernel/cpu/cpu.c b/src/kernel/cpu/cpu.c
index d27cb27..4c678d2 100644
--- a/src/kernel/cpu/cpu.c
+++ b/src/kernel/cpu/cpu.c
@@ -9,9 +9,10 @@ struct cpu __seg_gs *cpu = 0;
 
 void cpu_init()
 {
+  // Set up cpu struct
   struct cpu *c = P2V(pmm_calloc());
   c->cpu = c;
-  write_msr(0xc0000102, (uint64_t)c);
+  write_msr(KERNEL_GS_BASE, (uint64_t)c);
   asm("swapgs");
 
   interrupt_init();
diff --git a/src/kernel/cpu/registers.S b/src/kernel/cpu/registers.S
index 2f0c7ea..fa9a113 100644
--- a/src/kernel/cpu/registers.S
+++ b/src/kernel/cpu/registers.S
@@ -49,7 +49,6 @@ read_msr:
   shl rdx, 32
   add rax, rdx
   ret
-
 .global write_msr
 write_msr:
   mov rcx, rdi
diff --git a/src/kernel/include/cpu.h b/src/kernel/include/cpu.h
index c34fdac..bc9e12c 100644
--- a/src/kernel/include/cpu.h
+++ b/src/kernel/include/cpu.h
@@ -26,5 +26,8 @@ uint64_t read_cr3();
 void write_cr3(uint64_t);
 uint64_t read_cr4();
 
+// Model Specific Registers
+// Functions defined in cpu/registers.S
 void write_msr(uint64_t reg, uint64_t value);
 uint64_t read_msr(uint64_t reg);
+#define KERNEL_GS_BASE 0xC0000102