STM32Cube Data-Only Project

[RHJ]

I'm trying to generate an s-record file that contains nothing but an array of data in flash - no executable code.  (This is used by an external tool and loaded into flash later as config data.)  I deleted everything from the project except main.c.  I also stripped everything out of the linker .ld file except the data array.  But the compiler still generates a _init and a _fini section of code.  How do I get rid of those?

main.c

const unsigned char Data_Arr[] __attribute__((section (".data_arr"))) = /* Test array */

{

0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18

};

 

.ld file

/* Memories definition */

MEMORY

{

FLASH (rx) : ORIGIN = 0x0801E000, LENGTH = 4K

}

 

/* Sections */

SECTIONS

{

.data_arr :

{

. = ALIGN(4);

KEEP (*(.data_arr))

} >FLASH

}

 

List file still contains:

Disassembly of section .init:

0801e000 <_init>:
801e000: b5f8 push {r3, r4, r5, r6, r7, lr}
801e002: bf00 nop

Disassembly of section .fini:

0801e004 <_fini>:
801e004: b5f8 push {r3, r4, r5, r6, r7, lr}
801e006: bf00 nop

 

S-Record

S010000054657374446174612E73726563FA
S3090801E000F8B500BFA1
S3090801E004F8B500BF9D
S30D0801E00811121314151617185D
S70500000000FA

 

Thanks for your help.

[Bob S]

The compiler/linker is always going to include the c/c++ startup code and other stuff.

How about srecord  https://srecord.sourceforge.net/ .  You can create a text file with hex values then use srec_cat to create the S-record (or almost any other format) formatted file.

[Tesla DeLorean]

Make those "NOLOAD" sections in the Linker Script ?

Making a PC side C app that simply outputs S-Records from an array shouldn't be that hard, format in use since the late 1970's. I've written patching / packaging tools that just natively output .HEX files in Intel, Motorola or Tektronix formats.

As Bob indicates SRECORD is a popular open source version.

I'd suppose OBJCOPY could also be run on a section level basis

[RHJ]

The real data array will be an array of structs about a K long, so it really needs to be compiled with a C compiler.

However, this seemed to work (linker script):

.text (NOLOAD) :

{

*(.init)

*(.fini)

} >FLASH

 

Thanks again for your help.