How does firmwware executes? Is it loaded into memory and process created ?
In: Technology
Devices that have firmware usually have a little computer (or microcontroller) of their own, on which it’s executed. Like routers, smart refrigerators, digital watches and such.
Firmware is what runs the thing (OS, basically), it creates functionality for the thing and sometimes provides communication with other devices, like computers or whatever.
Also, it’s kind of important to make distinction between firmware and drivers. They’re a bit different thing.
It can be hard to define what firmware is. When the term first came about it was used to describe the code that was loaded into Read Only Memory modules. This code could never be changed without physically changing the ROM chips. This was different from the code you found in RAM or on disk or tape which could be changed at runtime. Of course these days we have ROM modules that can be reprogrammed in order to upgrade the code on it. But it tends to be code that rarely gets changed and that gets issued by the manufacturer rather then chosen by the user.
With regards to the firmware that runs on your processor this is usually the BIOS. It sits on a chip on the motherboard. It is not loaded into memory but it rather acts as memory. The default state that all the memory handling systems is hard coded to be in when power is applied will ensure that the processor is executing code from the firmware rather then the memory. The firmware then sets up everything else on the computer and read code from the hard drive into memory which it then executes as the bootloader.
But the BIOS is only one piece of firmware on your computer. A lot of systems in your computer are running a microprocessor of some kind. Your hard drive have a microprocessor with firmware, your network card, each of your USB controllers, your power supply, sound card, etc. Even your processor have at least one microprocessor in it to do various different things. And most of these microprocessors have some firmware that they run stored on a different part of the chip from the main microprocessor. This firmware is usually not booting another piece of software like your BIOS and will remain executing the firmware until you power it down.
Firmware is just software that runs in some sort of read-only (typically flashable) storage. There’s typically no “process” as there is either no kernel (no need for anything else to run) or a very minimal one as it directly controls the hardware.
As for how it’s started, most CPUs will begin executing code from a fixed memory address as part of the design. On x86 this is 0xFFFFFFF0
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