Use different arm-none-eabi-* version to build projects

I’m using Ubuntu 16.0 with arm-none-eabi-gcc version 5.4.1 installed from PPA, i think platformio uses 4.8 version.
Is it possible to change platformio to use the 5.4.1 version?

Also i would like to get the assembly generated by arm-none-eabi-gcc, this is achieved with the switch -S, but when i add it to build_flags on the .ini file i got a linking error.
Here’s my .ini file:

platform = ststm32
board = disco_f407vg
framework = libopencm3
build_flags = -S -O2

Is this written properly?, i just start using platformio, it’s been a very good developing experience :smiley:

Thanks in advance