After changing the GCC version, make[1] appears in the compilation: cc: command not found

Replaced the lower version GCC after , compile mbedtls The library will report this error

If you don't want to switch back to the default GCC edition , Can be in makefile Add the following two sentences

export CC       := gcc 
export CXX      := g++

If you are prompted bignum.c:1994: error: ‘for’ loop initial declarations are only allowed in C99 mode
bignum.c:1994: note: use option -std=c99 or -std=gnu99 to compile your code

You can change to

export CC       := gcc -std=c99 -std=gnu99
export CXX      := g++