esp8266/tools/sdk/lib/README.md

Updating SDK libraries

After updating SDK libraries to a new version, do the following changes.

Remove mem_manager.o from libmain.a to use custom heap implementation, and time.o to fix redefinition of time-related functions:

xtensa-lx106-elf-ar -d libmain.a mem_manager.o
xtensa-lx106-elf-ar -d libmain.a time.o

Rename hostname and default_hostname symbols:

xtensa-lx106-elf-ar x libmain.a eagle_lwip_if.o user_interface.o
xtensa-lx106-elf-objcopy --redefine-sym hostname=wifi_station_hostname user_interface.o 
xtensa-lx106-elf-objcopy --redefine-sym hostname=wifi_station_hostname eagle_lwip_if.o 
xtensa-lx106-elf-objcopy --redefine-sym default_hostname=wifi_station_default_hostname user_interface.o 
xtensa-lx106-elf-objcopy --redefine-sym default_hostname=wifi_station_default_hostname eagle_lwip_if.o 
xtensa-lx106-elf-ar r libmain.a eagle_lwip_if.o user_interface.o 

Updating libstdc++

After building gcc using crosstool-NG, get compiled libstdc++ and remove some objects:

xtensa-lx106-elf-ar d libstdc++.a pure.o
xtensa-lx106-elf-ar d libstdc++.a vterminate.o
xtensa-lx106-elf-ar d libstdc++.a guard.o
xtensa-lx106-elf-ar d libstdc++.a functexcept.o
xtensa-lx106-elf-ar d libstdc++.a del_op.o
xtensa-lx106-elf-ar d libstdc++.a del_opv.o
xtensa-lx106-elf-ar d libstdc++.a new_op.o
xtensa-lx106-elf-ar d libstdc++.a new_opv.o