On Wed, Mar 04, 2009 at 10:15:21AM +0000, wei yang wrote:
When I use the seabios as the payload, I got a strange issue. In the seabios flow:
Post->timer_setup->rtc_updating->inb_cmos function
when run the inb_cmos, it will reboot on the inb operation.
inb_cmos disassemables to fllowing: out 0x70, value in value, 0x71. ----> run here to make the reboot happen.
0x70 is the CMOS index port, 0x71 is the CMOS data port.
I suspect the "in value, 0x71" operation causes a exception and the seabios doesn't have real IDT, so it then make the reboot.
but why it cause the exception is a question for me?
since IO port 0x70 also reponsible for the NMI enble/disable, is it caused the error?
I haven't seen this before. It would be odd for port 0x70 to control NMI, because it is usually used for rtc access.
-Kevin