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im creating an os for fun and i allready jumped to the kernel and i am in protected mode.

I setup the GDT and IDT in the kernel and everything seems to work but if i try to run an infinite loop in C afterwards (anything eg. for(;;),while(1)...) it generates a double fault (i catched the double fault to display an error).

But if i remove the CPU_initGDT and CPU_initIDT (both set the IDT or GDT table to appropriate values and run lidt and lgdt) it works fine.
(im allready setting a default GDT in the second stage bootloader )

Did anyone had this problem and how did he/she fix it ?

thanks in advance

Hi,

SeeSoftware wrote:Did anyone had this problem and how did he/she fix it ?

I'd be tempted to guess that your "CPU_initIDT" enables IRQs and nothing has reconfigured the PIC chips; which means that when the PIT timer causes an IRQ0 it's mapped to interrupt 0x08 (and the "interrupt 0x08" you see is not actually a double fault).


Cheers,

Brendan

Brendan wrote:Hi,

SeeSoftware wrote:Did anyone had this problem and how did he/she fix it ?

I'd be tempted to guess that your "CPU_initIDT" enables IRQs and nothing has reconfigured the PIC chips; which means that when the PIT timer causes an IRQ0 it's mapped to interrupt 0x08 (and the "interrupt 0x08" you see is not actually a double fault).


Cheers,

Brendan

ahh thank you it makes sense because if i clear the interrupt flag then it will run fine because the IRQs wont fire (or something)

Setting the PIC fixed my problem thank you Brendan