Memory sections in linker script

[Laurent]

By the way, my .map file contains this:

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 *(.bss.*)
                0x20005740                . = ALIGN (0x4)
 *(COMMON)
 COMMON          0x20005740        0xa CMakeFiles/test.dir/main.c.obj
                0x20005740                my_var

So how should I refer to my variable in the linker script?

[pito]

This works for me - I've tried to place my two float arrays (re[], im[], 32kB each) into CCM:

In the linker script add:

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..
    .ccm :
    {
        KEEP(*(.ccmbuf))
    } > ccmram

And in the main.c for example:

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..
#define intoCCM  __attribute__((section(".ccmbuf")))  __attribute__((aligned(4)))
#define N 8192

float re[N] intoCCM;
float im[N] intoCCM;

That places the two arrays into CCM memory section - see the map file:

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..
.ccm            0x10000000    0x10000
 *(.ccmbuf)
 .ccmbuf        0x10000000    0x10000 build/obj/main.o
                0x10000000                re
                0x10008000                im

.bss            0x20000c38    0x183c8

This way I put 5x32kB of arrays into the STMF4:

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..
#define intoCCM  __attribute__((section(".ccmbuf")))  __attribute__((aligned(4)))
#define N 8192

float re[N] intoCCM;
float im[N] intoCCM;

float test[N];
float test1[N];
float test2[N];
..

If the vars do not fit into the CCM you will get an error:

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..
#define N 8192
float re[N] intoCCM;
float im[N] intoCCM;
float re1[100] intoCCM;

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.../arm-none-eabi/bin/ld.exe: region `ccmram' overflowed by 400 bytes
collect2.exe: error: ld returned 1 exit status