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This is a very simple question. What's the difference between a cold boot and a warm boot? This has been bothering me for a few days now, and I just want to get it out of my head.

IIRC cold boots are from no power and warm boots are a reboot. I think.

EDIT: Yeah, cold boot is resetting the power and warm boot is like a software reboot (no power change.)

Troy Martin wrote:IIRC cold boots are from no power and warm boots are a reboot. I think.

EDIT: Yeah, cold boot is resetting the power and warm boot is like a software reboot (no power change.)

Even warm boots could have double meaning. The software could invoke the processor to reboot just as pressing the reset button could, or the OS loads the bootloader and jumps into it self, effectively doing the whole thing in software and avoiding POST. Perhaps some OS's take this a step further and just unload and reload all modules, and reset all kernel variables.

A cold boot refers to a power cycle on the hardware.

A warm boot (aka Int 19h) refers to IPL usually controlled by the BIOS but the OS could also simulate one. In essence a warm boot could be initiated by setting the initial processor state to what it is with a cold boot. Other hardware would also have to be "reset" otherwise drivers would get it in an unexpected state when they load initially in the OS. The requirement for hardware reset is best done by the BIOS as it knows most about the controllers attached to the devices.

An alternative method of Warm boot would be for the BIOS to "press" the reset button on the motherboard which is probably what most BIOSes would do to keep the process simple and consistent.