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Hi,

Ive recently started programming for the x86_64 and have successfully entered long mode, the problem i am having is with enabling interrupts when using
sti - I am getting a General protection fault.
{works fine in Real & 32PMode}


I was wondering if anyone has come accross this problem and knows how to solve it.

I have googled but am yet to find anything to help.

bye pkd.

pkd wrote: Hi,

Ive recently started programming for the x86_64 and have successfully entered long mode, the problem i am having is with enabling interrupts when using
sti - I am getting a General protection fault.
{works fine in Real & 32PMode}


I was wondering if anyone has come accross this problem and knows how to solve it.

My guess is on the interrupt stack mechanism x86_64 introduced. I don't have any experience with interrupts in it, so I can't help you there.

Hi again,

Still havent got it working yet, but am about to compile bochs and hopefully willmget some extended error information, Ill post again if i work it out.

Thanks for your reply.

bye pkd.

hi again,

Ive got it fixed sortof, for some reason the first STI is causing a General protection fault but once ive been through the exception handler once STI works fine

It is a bit of a workaround but at least i can get on with writing now.

By the way it works without the #GP in bochs

To do this ive added the following code.{ rcx points to the return address}

   mov   rcx,Entry
   call   0x11000 ;My current INT/Exception Setup
Entry:
   mov   rsi,EntryMsg
   mov   rdi,0xb8a00
   call   print64

   mov   r15,0x1234567812345678 ;my STI signature
   sti            

END:
   hlt
   jmp   END   ;TEMP MSGLOOP

and this to my exception handler for #GP

Setup ints/Exceptions

mov   rdi,ENTRY ;this just stores the iretq return address
   mov   [rdi],rcx

;-------------------------------------------------
Exc13:
   mov   r14,0x1234567812345678 ;check for STI signature
   cmp   r15,r14
   jnz   Exc13a

         add   rsp,8
         mov   rdi,[ENTRY]
         mov   [rsp],rdi

         iretq

Exc13a:
   mov   rsi,Ex13txt
   jmp   ExcPrint

ok bye
pkd.