Changeset d242cb6 in mainline for kernel/arch/ia32/src/boot/vesa_real.inc

Timestamp:

2013-05-13T22:34:28Z (11 years ago)

Author:

Martin Decky <martin@…>

Branches:

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

Children:

6e8ed225

Parents:

959d2ec

Message:

make sure we configure two distinct segment descriptors and set the read bit on the code segment before switching back to real-mode for VESA/VBE
this fixes execution on the latest (3.9.1) Linux KVM with real-mode x86 code emulation that is particularly picky about the code segment permission bits

File:

• kernel/arch/ia32/src/boot/vesa_real.inc (modified) (3 diffs)

kernel/arch/ia32/src/boot/vesa_real.inc

@@ -31 +31 @@
 vesa_init:
         lidtl vesa_idtr
-        jmp $GDT_SELECTOR(VESA_INIT_DES), $vesa_init_real - vesa_init
+        
+        mov $GDT_SELECTOR(VESA_INIT_DATA_DES), %bx
+        
+        mov %bx, %es
+        mov %bx, %fs
+        mov %bx, %gs
+        mov %bx, %ds
+        mov %bx, %ss
+        
+        jmp $GDT_SELECTOR(VESA_INIT_CODE_DES), $vesa_init_real - vesa_init
 
 vesa_idtr:
@@ -39 +48 @@
 .code16
 vesa_init_real:
-        
         mov %cr0, %eax
         and $~1, %eax
@@ -45 +53 @@
         
         jmp $VESA_INIT_SEGMENT, $vesa_init_real2 - vesa_init
-        
+
 vesa_init_real2:
         mov $VESA_INIT_SEGMENT, %bx