I'm writing an embedded program, divided in two parts: bootloader and app. (I'm using STM32, eclipse) I'm usign a display, so I wrote some function and 3 different fonts. The idea is to use a sector of the microcontroller and share it. The font area is defined with Ld script like

 .mySegment start_of_FONT_segm : {KEEP(*(.Courier_New_Bold_20_Section))}
 .mySegment1 0x8011298 : {KEEP(*(.Terminal6x8_Section))}

and use an array to write in

const unsigned char __attribute__((section (".Terminal6x8_Section"))) Terminal6x8[] = {
   0x00,
   0x00,
   ...

But how to read it from another program (in this case, the Aplication?) I tried with

unsigned char *Terminal6x8 = (volatile unsigned char*)0x08011298;

but the compiler put the 'Terminal6x8' into RAM. I'll be glad to share some functions also, but don't know how to declare in ld and C sintax too.

Any suggestions?

CodePudding user response：

Indeed the pointer *Terminal6x8 is put into RAM. If you want the pointer stored in flash, declare it const.

Although, the data pointed to by *Terminal6x8 is stored in flash at address 0x08011298 as you want. No matter where the pointer is stored.

CodePudding user response：

unsigned char *Terminal6x8 = (volatile unsigned char*)0x08011298;

Is bad in many means.

1. Uses fixed address which is not very good
2. Declares the data as volatile which makes no sense in this context
3. Data is not declared as constant.

If you want to pointer to be also placed in the FLASH memory

const unsigned char * const Terminal6x8 = (const unsigned char * const) 0x08011298;

I'll be glad to share some functions also

How to do it properly?

You need to declare a vector table (pointer table) containing the pointers to data and functions you want to share.