ESP8266 Community Forum

Hi,
I'm a little confused about bootloaders on the esp8266.
I know there are different version of the sdk, each version has its own bootloader binary blob (boot_1.1.bin, boot_1.2.bin, boot_1.3.bin, etc) and from the 1.2 version of the sdk the format of the user apps rom is different (0x09 or 0xea).

So, assuming it's correct, the questions are:
-what's the difference between all these versions?
-can I use a bootloader from another sdk version? (both >= 1.2)
-is any version ok for the OTA upgrade?

Probably I could use directly the latest version without worry about the others, but I prefer to understand the differences and I wasn't able to find any release note / changelog information about bootloaders.

Thanks in advice

Since there is no public documentation on the bootloader releases, only espressif can answer those questions. You might have better luck at getting an answer if you ask on the official espressif forum or send an email to their support.

That being said, if you want to understand what happens in the bootloader, I would recommend using open source "rboot".
https://github.com/raburton/esp8266/tree/master/rboot

Thank you!
I had already studied rBoot and it's a perfect example for understanding the mechanism but I'd like to understand the sdk version too, so I'll ask to Espressif and eventually I'll share the info