Changeset dcbc8be in mainline for arch/ia32/src/boot/boot.S

Timestamp:

2005-06-02T23:56:26Z (20 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

ac5d02b

Parents:

7dcbc0a1

Message:

Big changes in IA-32 address space map.
Now the kernel is mapped above 0x80000000. Finally!
Userspace address space starts at 0x00000000.
Changes in many places.
This improvement temporarily breaks SMP and most likely also other stuff.
Supported size of memory is now only 4M as it is the biggest size that can be mapped at once on IA-32.

Changes in linker script.
Changes required because of the above.
Do not patch hardcoded_* variables but assign to them instead.

Cosmetic changes here and there.

File:

• arch/ia32/src/boot/boot.S (modified) (2 diffs)

arch/ia32/src/boot/boot.S

@@ -40 +40 @@
 #
 kernel_image_start:
+        cli
         call memmap_arch_init
-        cli
         xorw %ax,%ax
         movw %ax,%ds
@@ -63 +63 @@
         lidt idtr
 
+        #
+        # Here we setup mapping for both the unmapped and mapped sections of the kernel.
+        # For simplicity, we set only one 4M page for 0x00000000 and one for 0x80000000.
+        #
+        movl %cr4, %ecx
+        orl $(1<<4), %ecx
+        movl %ecx, %cr4                         # turn PSE on
+        
+        movl $((1<<7)|(1<<0)), %eax
+        movl %eax, page_directory               # mapping 0x00000000 => 0x00000000
+
+        movl $(page_directory+(4096/2)), %edx
+        movl %eax, (%edx)                       # mapping 0x80000000 => 0x00000000
+
+        leal page_directory, %eax
+        movl %eax, %cr3
+        
+        # turn on paging
+        movl %cr0, %ebx
+        orl $(1<<31), %ebx
+        movl %ebx, %cr0
+
+        movl $_hardcoded_ktext_size, hardcoded_ktext_size
+        movl $_hardcoded_kdata_size, hardcoded_kdata_size
+        movl $_hardcoded_load_address, hardcoded_load_address
+
         call main_bsp                   # never returns
-        
 
         cli
         hlt
+
+.section K_DATA_START
+
+.align 4096
+page_directory:
+        .space 4096, 0