Question about new changes in SDK guide V3.0 and possible mistakes in document

[jj8431]

Hi Everyone,

I'm learning ESP8266 and encountered some questions I can't find answer, if anyone here has the same question or know the answer I would appreciate very much!

First, the official document ESP8266-SDK_Getting_Started_Guide has a new version V3.0 recently, compare to its earlier version V2.8, some parts have been removed. Especially this one:
in charpter 3.3.2, there were some words about the location of master_device_key.bin (see screen shot 1), but it's removed in V3.0 (screen shot 2). To my understanding this file is about the communication with espressif IoT cloud server, does the removal means it's not needed any more?
screenshot 1:

screenshot 2:

The second question, in both V2.8 and V3.0 documents, in chapter 5.1 mentioned about modifying the source code in SDK according to the flash size before compiling, (see screenshot 3), but I coun't find these lines in any file in the SDK, anybody know what's going on here?
screenshot 3:

[Her Mary]

master_device_key.bin is a part/example of user data. It is needed if you are using ESP cloud. And if you do not use the ESP cloud, there is no need to download master_device_key.bin.