ARM Compiler toolchain Using the Linker - ARM Information Center

8.18 Using __attribute__((section("name")))
8.18.1 See also
Using scatter files
You can place code and data by separating them into their own objects without having to use
toolchain-specific pragmas or attributes. However, you can also use
__attribute__((section("name"))) to place an item in a separate ELF section. You can then use
a scatter file to place the named sections at specific locations.
To use __attribute__((section("name"))) to place a variable in a separate section:
1. Use __attribute__((section("name"))) to specify the named section where the variable is
to be placed, for example:
int variable __attribute__((section("foo"))) = 10;
2. Use a scatter file to place the named section, for example:
FLASH 0x24000000 0x4000000
{
... ; rest of code
}
ADDER 0x08000000
{
file.o (foo) ; select section foo from file.o
}
Be aware of the following:
• linking with --autoat or --no_autoat does not affect the placement
Example 8-8 Naming a section
Example 8-9 Placing a section
• if scatter-loading is not used, the section is placed in the default ER_RW execution region of
the LR_1 load region
• if you have a scatter file that does not include the foo selector, then the section is placed
in the defined RW execution region.
You can also place a function at a specific address using .ARM.__at_address as the section name.
For example, to place the function sqr at 0x20000, specify:
int sqr(int n1) __attribute__((section(".ARM.__at_0x20000")));
int sqr(int n1)
{
return n1*n1;
}
Reference
• Using __at sections to place sections at a specific address on page 8-37
• Restrictions on placing __at sections on page 8-38.
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