Friends,
I have a very basic mqtt ping-pong program written in C/C++. I'm compiling it using mostly SDK CMake with MinSizeRel. The code is here: https://github.com/jaguilar/pico_experi ... lo_mqtt.cc
The size of my bin file for this simple program is 350kB. I have some questions. Here is the header of the .dis file printed by the SDK:
Question 1: Why, if I'm building with MinSizeRel, is there so much .debug stuff in the binary? Is it possible to reduce the amount of this stuff in my final release?
Question 2: For a program with lwip (DNS, MDNS, TCP, MQTT), FreeRTOS, the cyw43 driver, and my little program, is 350kB an expected amount of code?
Question 3: What's in .rodata? I did objdump -s -j .rodata build/src/hello_mqtt/hello_mqtt.elf and saw some stuff that makes sense to me:
But also a bunch of space that doesn't seem to have anything identifiable in it:
How do I tell what's in .rodata and whether it's needed?
Question 4: Why does my program contain unwind functions even though my compile commands are disabling unwind and exceptions?
Here is my compile command for my only cc file:
Note -fno-exceptions and -fno-unwind-tables. Is there more that needs to be done to disable this code? It seems to be about 1/6th of the total code as printed in the .dis file, so it seems like it would be nice to get it out of the result.
Thank you in advance for sharing your expertise on these issues!
I have a very basic mqtt ping-pong program written in C/C++. I'm compiling it using mostly SDK CMake with MinSizeRel. The code is here: https://github.com/jaguilar/pico_experi ... lo_mqtt.cc
The size of my bin file for this simple program is 350kB. I have some questions. Here is the header of the .dis file printed by the SDK:
Code:
/home/jaguilar/projects/pico_experiments/build/src/hello_mqtt/hello_mqtt.elf: file format elf32-littlearmSections:Idx Name Size VMA LMA File off Algn 0 .boot2 00000100 10000000 10000000 00001000 2**0 CONTENTS, ALLOC, LOAD, READONLY, CODE 1 .text 00019b28 10000100 10000100 00001100 2**4 CONTENTS, ALLOC, LOAD, READONLY, CODE 2 .rodata 0003a07c 10019c28 10019c28 0001ac28 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA 3 .ARM.extab 000000f0 10053ca4 10053ca4 00054ca4 2**2 CONTENTS, ALLOC, LOAD, READONLY, DATA 4 .ARM.exidx 000001d0 10053d94 10053d94 00054d94 2**2 CONTENTS, ALLOC, LOAD, READONLY, DATA 5 .binary_info 00000020 10053f64 10053f64 00054f64 2**2 CONTENTS, ALLOC, LOAD, READONLY, DATA 6 .ram_vector_table 000000c0 20000000 20000000 00058000 2**2 ALLOC 7 .data 000022ac 200000c0 10053f84 000550c0 2**4 CONTENTS, ALLOC, LOAD, READONLY, CODE 8 .uninitialized_data 00000020 20002370 10056230 00057370 2**3 ALLOC 9 .scratch_x 00000000 20040000 20040000 0005736c 2**0 CONTENTS 10 .scratch_y 00000000 20041000 20041000 0005736c 2**0 CONTENTS 11 .bss 00022430 20002390 20002390 00057390 2**3 ALLOC 12 .heap 00000800 200247c0 200247c0 0005736c 2**2 CONTENTS, READONLY 13 .stack1_dummy 00000800 20040000 20040000 00058000 2**2 ALLOC 14 .stack_dummy 00000800 20041000 20041000 00057b80 2**5 CONTENTS, READONLY 15 .ARM.attributes 00000028 00000000 00000000 00058380 2**0 CONTENTS, READONLY 16 .comment 00000059 00000000 00000000 000583a8 2**0 CONTENTS, READONLY 17 .debug_info 0004a178 00000000 00000000 00058401 2**0 CONTENTS, READONLY, DEBUGGING, OCTETS 18 .debug_abbrev 000098fd 00000000 00000000 000a2579 2**0 CONTENTS, READONLY, DEBUGGING, OCTETS 19 .debug_loclists 00015ee6 00000000 00000000 000abe76 2**0 CONTENTS, READONLY, DEBUGGING, OCTETS 20 .debug_aranges 00001170 00000000 00000000 000c1d60 2**3 CONTENTS, READONLY, DEBUGGING, OCTETS 21 .debug_rnglists 000034f5 00000000 00000000 000c2ed0 2**0 CONTENTS, READONLY, DEBUGGING, OCTETS 22 .debug_line 0001335b 00000000 00000000 000c63c5 2**0 CONTENTS, READONLY, DEBUGGING, OCTETS 23 .debug_str 0000c138 00000000 00000000 000d9720 2**0 CONTENTS, READONLY, DEBUGGING, OCTETS 24 .debug_frame 00002e70 00000000 00000000 000e5858 2**2 CONTENTS, READONLY, DEBUGGING, OCTETS 25 .debug_line_str 000000a3 00000000 00000000 000e86c8 2**0 CONTENTS, READONLY, DEBUGGING, OCTETS 26 .debug_loc 00003faa 00000000 00000000 000e876b 2**0 CONTENTS, READONLY, DEBUGGING, OCTETS 27 .debug_ranges 000001c8 00000000 00000000 000ec715 2**0 CONTENTS, READONLY, DEBUGGING, OCTETSQuestion 2: For a program with lwip (DNS, MDNS, TCP, MQTT), FreeRTOS, the cyw43 driver, and my little program, is 350kB an expected amount of code?
Question 3: What's in .rodata? I did objdump -s -j .rodata build/src/hello_mqtt/hello_mqtt.elf and saw some stuff that makes sense to me:
Code:
10019cf8 00657272 6f722063 6f6e6e65 6374696e .error connectin 10019d08 6720746f 206d7174 743a2025 640a0077 g to mqtt: %d..w 10019d18 72697465 72002f70 696e6700 6572726f riter./ping.erro 10019d28 72207375 62736372 6962696e 6720746f r subscribing to 10019d38 206d7174 743a2025 730a0062 61736963 mqtt: %s..basic 10019d48 5f737472 696e673a 3a5f4d5f 7265706c _string::_M_repl 10019d58 61636500 6d6f7265 20746861 6e207468 ace.more than th 10019d68 65206578 70656374 6564206e 756d6265 e expected numbeCode:
1001d9a8 000a3268 354805f0 81d9a36c 21680093 ..2h5H.....l!h.. 1001d9b8 636c2246 0193a368 31480293 e3680027 cl"F...h1H...h.' 1001d9c8 0393e36c 05f072d9 e36904f1 10010093 ...l..r..i...... 1001d9d8 236a2c48 0193636a 4fea9a0a 0293a36a #j,H..cjO......j 1001d9e8 b9460393 0ec905f0 61d9a36b 04f12c01 .F......a..k..,. 1001d9f8 0093e36b 24480193 236cb846 02930ec9 ...k$H..#l.F.... 1001da08 05f054d9 eb682148 009395e8 0e0005f0 ..T..h!H........ 1001da18 4dd9eb69 05f11001 00931d48 0ec905f0 M..i.......H.... 1001da28 45d918e0 7a59d307 0fd5ff2a 0dd9194b E...zY.....*...KQuestion 4: Why does my program contain unwind functions even though my compile commands are disabling unwind and exceptions?
Code:
10017a40 <_ZL21base_of_encoded_valuehP15_Unwind_Context>:10017a40:0002 movsr2, r010017a42:b510 push{r4, lr}10017a44:0008 movsr0, r110017a46:2aff cmpr2, #255@ 0xff10017a48:d010 beq.n10017a6c <_ZL21base_of_encoded_valuehP15_Unwind_Context+0x2c>10017a4a:2370 movsr3, #112@ 0x7010017a4c:4013 andsr3, r2Code:
/usr/bin/arm-none-eabi-g++ -DCFG_TUSB_MCU=OPT_MCU_RP2040 \ -DCFG_TUSB_OS=OPT_OS_PICO -DCYW43_LWIP=1 -DFREE_RTOS_KERNEL_SMP=1\ -DLIB_FREERTOS_KERNEL=1 -DLIB_PICO_ASYNC_CONTEXT_FREERTOS=1 \ -DLIB_PICO_BIT_OPS=1 -DLIB_PICO_BIT_OPS_PICO=1 -DLIB_PICO_CYW43_ARCH=1 \ -DLIB_PICO_DIVIDER=1 -DLIB_PICO_DIVIDER_HARDWARE=1 -DLIB_PICO_DOUBLE=1 \ -DLIB_PICO_DOUBLE_PICO=1 -DLIB_PICO_FIX_RP2040_USB_DEVICE_ENUMERATION=1 \ -DLIB_PICO_FLOAT=1 -DLIB_PICO_FLOAT_PICO=1 -DLIB_PICO_INT64_OPS=1 \ -DLIB_PICO_INT64_OPS_PICO=1 -DLIB_PICO_MALLOC=1 -DLIB_PICO_MEM_OPS=1 \ -DLIB_PICO_MEM_OPS_PICO=1 -DLIB_PICO_MULTICORE=1 -DLIB_PICO_PLATFORM=1 \ -DLIB_PICO_PRINTF=1 -DLIB_PICO_PRINTF_PICO=1 -DLIB_PICO_RAND=1 \ -DLIB_PICO_RUNTIME=1 -DLIB_PICO_STANDARD_LINK=1 -DLIB_PICO_STDIO=1\ -DLIB_PICO_STDIO_USB=1 -DLIB_PICO_STDLIB=1 -DLIB_PICO_SYNC=1 \ -DLIB_PICO_SYNC_CRITICAL_SECTION=1 -DLIB_PICO_SYNC_MUTEX=1 \ -DLIB_PICO_SYNC_SEM=1 -DLIB_PICO_TIME=1 -DLIB_PICO_UNIQUE_ID=1 \ -DLIB_PICO_UTIL=1 -DLWIP_PROVIDE_ERRNO=1 -DPICO_BOARD=\\\"pico_w\\\" \ -DPICO_BUILD=1 -DPICO_CMAKE_BUILD_TYPE=\\\"MinSizeRel\\\" -DPICO_CONFIG_RTOS_ADAPTER_HEADER=/home/jaguilar/projects/pico_experiments/lib/FreeRTOS/FreeRTOS/Source/portable/ThirdParty/GCC/RP2040/include/freertos_sdk_config.h \ -DPICO_COPY_TO_RAM=0 -DPICO_CXX_ENABLE_EXCEPTIONS=0 -DPICO_CYW43_ARCH_FREERTOS=1 \ -DPICO_NO_FLASH=0 -DPICO_NO_HARDWARE=0 -DPICO_ON_DEVICE=1 \ -DPICO_RP2040_USB_DEVICE_UFRAME_FIX=1 -DPICO_TARGET_NAME=\\\"hello_mqtt\\\" \ -DPICO_USE_BLOCKED_RAM=0 SNIP_INCLUDE_DIRECTORIES -mcpu=cortex-m0plus \ -mthumb -Os -DNDEBUG -Wall -Wno-format -Wno-unused-function -fdata-sections \ -ffunction-sections -DMQTT_HOST=\\\"rpi5.local\\\" -DMQTT_USER=\\\"jags_mqtt\\\" \ -DMQTT_PASSWORD=\\\"SECRET\\\" -fno-exceptions -fno-unwind-tables -fno-rtti \ -fno-use-cxa-atexit -std=gnu++20 -o CMakeFiles/hello_mqtt.dir/hello_mqtt.cc.obj\ -c /home/jaguilar/projects/pico_experiments/src/hello_mqtt/hello_mqtt.ccThank you in advance for sharing your expertise on these issues!
Statistics: Posted by jags84 — Fri Mar 29, 2024 2:02 pm