Boot sequence of embedded system

[sudhanwaaa]

Hello friends,
I am studying sequence in which Embedded system boots assuming its an embedded linux based system.I am studying this by drawing paralles with PC Boot sequence where BIOS,POST,MBR,First stage Bootloader and so on sequence is...
So here my query is where does exactly MBR fit in during Embedded system boot sequence.
Is there any parallel terminology with respect to embedded system boot up.
Plz explain this with example of raspberry pi booting from SD card....specifically want info about MBR

 

[mfro]

Plz explain this with example of raspberry pi booting from SD card....specifically want info about MBR

This is simple to explain: conceptually, there is basically no difference between booting Linux on the RPi or any other (PC) system.

Simply because the Pi cannot be considered an embedded system in this regard - its more like a (tiny) PC.

 

[c_mitra]

Both POST and BIOS are executed before the boot process kicks in. Both POST and BIOS reside in the system ROM and they provide support for the boot process.

 

[sudhanwaaa]

So, Where Does MBR,PBR,IPL come in this case of booting sequence ?

 

[srizbf]

No BIOS,POST and MBR in embedded environment.
Though you can understand the sequence , it is for a PC environment.
Your Raspberry will have only a bootlaoader that may read from SD card .
And SD cards have FAT32 systems (BootRecord,FAT, Filedirectory ..)

 

[Driftus]

BIOS -> MBR -> bootloader is a PC-specific sequence. Embedded systems usually refer to MBR only to access the partition table of the storage.

Usually the board's SoC has firmware that's written in it's ROM during production. The firmware performs the initial initialization of the hardware and then tries to boot an OS. The way it is done is implementation-specific, but all boils down to finding a bootloader code somehow.

For example, Raspberry Pi 2's firmware is smart enough to detect SD card and find bootloader on one of the partitions (follow this link, the last section on the page - Standalone booting).

H3/H2+-based Orange Pi's just load bootloader from particular sections of the SD card and pass control to it: https://linux-sunxi.org/Bootable_SD_card
(not sure the sequence is clearly defined on the page, but if you delve further into the wiki you'll find that info)