From 3122de1666c5fb026a069bb1fa986ad9f470d4a0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Lov=C3=A9n?= <thomasloven@gmail.com>
Date: Mon, 5 Feb 2018 14:09:36 +0100
Subject: [PATCH] Remove cpuid and longmode checks. Let's assume we have a
 modern processor

---
 src/kernel/boot/boot.S | 52 +-----------------------------------------
 1 file changed, 1 insertion(+), 51 deletions(-)

diff --git a/src/kernel/boot/boot.S b/src/kernel/boot/boot.S
index 4dbd047..087800f 100644
--- a/src/kernel/boot/boot.S
+++ b/src/kernel/boot/boot.S
@@ -10,63 +10,13 @@ BootStack:
 .section .text
 
 .code32
-error:
-  //; Print "ERR!" in upper left corner
-  mov [0xb8000], dword ptr 0x4f004f00
-  mov [0xb8004], dword ptr 0x4f004f00
-  mov [0xb8000], byte ptr 'E'
-  mov [0xb8002], byte ptr 'R'
-  mov [0xb8004], byte ptr 'R'
-  mov [0xb8006], byte ptr '!'
-  jmp $
-
-check_cpuid:
-  //; Save EFLAGS
-  pushfd
-
-  //; Try to modify EFLAGS.ID
-  pushfd
-  xor dword ptr [esp], 1<<21
-  popfd
-
-  //;Read EFLAGS into eax
-  pushfd
-  pop eax
-
-  //; Restore original EFLAGS
-  popfd
-
-  //; Check if EFLAGS.ID was modified
-  xor eax, [esp+4]
-  and eax, 1<<21
-  jz error
-  ret
-
-check_longmode:
-  //; cpuid 0x8000 0000
-  mov eax, 0x80000000
-  cpuid
-  cmp eax, 0x80000001
-  jb error
-
-  //; cpuid 0x8000 0001
-  mov eax, 0x80000001
-  cpuid
-
-  //; Test for long mode flag
-  test edx, 1<<29
-  jz error
-  ret
-
 .global _start
 _start:
   cli
 
+  //; Set up a known stack
   mov esp, offset BootStack
 
-  call check_cpuid
-  call check_longmode
-
   //; Set CR4.PAE
   //; enabling Page Address Extension
   mov eax, cr4