ESP8266 Community Forum

- Sat Nov 15, 2014 5:10 pm #2694 Hi,

this is for anyone interested in using objcopy instead of esptool, and to be able to use objdump to show disassembly from firmware images more easily. I've implemented a libbfd target called espimage. See https://github.com/tommie/binutils-gdb/tree/xtensa, a fork of binutils 2.24 with crosstool-NG patches (upstream and jcmvbkbc's). There are probably bugs in there, it's my first libbfd target module and a Saturday hack.

E.g. show all headers:

Code: Select all$ objdump -b espimage -x eagle.app.v6.flash.bin
eagle.app.v6.flash.bin:     file format espimage
eagle.app.v6.flash.bin
architecture: xtensa, flags 0x00000000:

start address 0x40100004

Sections:
Idx Name          Size      VMA               LMA               File off  Algn
  0 .text         00005e44  40100000  00000010  00000010  2**0
                  CONTENTS, ALLOC, LOAD, ROM
  1 .data         00000dbc  3ffe8000  00005e5c  00005e5c  2**0
                  CONTENTS, ALLOC, LOAD, ROM
  2 .data3        000018ac  3ffe8dc0  00006c20  00006c20  2**0
                  CONTENTS, ALLOC, LOAD, ROM
SYMBOL TABLE:
no symbols


Create an upgrade image from an ELF executable:

Code: Select all$ objcopy -j .text -j .data -j .rodata -O espimage eagle.app.v6.out eagle.app.v6.flash.bin


It doesn't output the sections in the same order as genflashbinv6, but rather by load address (as produced by the linker). I would guess it doesn't matter, but haven't tried an image yet. The trivial test of doing a copy from espimage to espimage shows no diffs:

Code: Select all$ objcopy -F espimage eagle.app.v6.flash.bin test.bin
$ cmp eagle.app.v6.flash.bin test.bin


Since the app firmware is split into two normally, I'm afraid letting the linker output firmware images directly is a no-no.