- Queried some values from pcr at DISPATCH_LEVEL to prevent from changing the processor after a thread switch.  
- Changed from bx to dx within inline assembler, because the ebx register must be saved.

reactos/ntoskrnl/ke/i386

diff -u -r1.17 -r1.18
--- gdt.c	15 Aug 2004 16:39:05 -0000	1.17
+++ gdt.c	31 Oct 2004 14:02:20 -0000	1.18
@@ -134,7 +134,7 @@

 	   "movl %1, %%fs\n\t"
 	   "movl %0, %%gs\n\t"
 	   : /* no output */

-	   : "a" (KERNEL_DS), "b" (PCR_SELECTOR));

+	   : "a" (KERNEL_DS), "d" (PCR_SELECTOR));

   __asm__ ("pushl %0\n\t"
 	   "pushl $.l4\n\t"
 	   "lret\n\t"

@@ -146,10 +146,10 @@

   {
     lgdt Descriptor;
     mov ax, KERNEL_DS;

-    mov bx, PCR_SELECTOR;

+    mov dx, PCR_SELECTOR;

     mov ds, ax;
     mov es, ax;

-    mov fs, bx;

+    mov fs, dx;

     mov gs, ax;
     push KERNEL_CS;
     push offset l4 ;

@@ -207,13 +207,14 @@

 		     PVOID Base)
 {
    KIRQL oldIrql;

-   PUSHORT Gdt = KeGetCurrentKPCR()->GDT;

+   PUSHORT Gdt;

    
    DPRINT("KeSetBaseGdtSelector(Entry %x, Base %x)\n",
 	   Entry, Base);
    
    KeAcquireSpinLock(&GdtLock, &oldIrql);
    

+   Gdt = KeGetCurrentKPCR()->GDT;

    Entry = (Entry & (~0x3)) / 2;
    
    Gdt[Entry + 1] = (USHORT)(((ULONG)Base) & 0xffff);

@@ -241,13 +242,14 @@

                  ULONG Value2)
 {
    KIRQL oldIrql;

-   PULONG Gdt = (PULONG) KeGetCurrentKPCR()->GDT;

+   PULONG Gdt; 

    
    DPRINT("KeSetGdtSelector(Entry %x, Value1 %x, Value2 %x)\n",
 	   Entry, Value1, Value2);
    
    KeAcquireSpinLock(&GdtLock, &oldIrql);
    

+   Gdt = (PULONG) KeGetCurrentKPCR()->GDT;;

    Entry = (Entry & (~0x3)) / 4;
 
    Gdt[Entry] = Value1;