generic arm cortex bootloader

Hi

is there any open source bootloader for arm cortex m*?

I have a series of boards (light LED control/ motor control ,...) controlled via CAN/LIN/Ethernet and would like to have a bootloader where certain things are shared:

the crc code, version numbering of the bootloader, a robust protokol to update it. ... may be integrated build/

 compile time of bootloader....

Stm32 comes with a bootloader example, but it is very basic. No version numbering ...

is there any open source bootloader for arm cortex m*?