ARM Compiler toolchain Using the Linker - ARM Information Center

2. Create the source file function.c containing the following code:
int sqr(int n1)
{
return n1*n1;
}
Using scatter files
3. Create the scatter file scatter.scat containing the following load region:
LR1 0x0
{
ER1 0x0
{
*(+RO) ; rest of code and read-only data
}
ER2 +0
{
function.o
*(.ARM.__at_0x10000) ; Place gValue at 0x10000
}
RAM 0x200000 (0x1FF00-0x2000) ; RW & ZI data to be placed at 0x200000
{
*(+RW, +ZI)
}
ARM_LIB_STACK 0x800000 EMPTY -0x10000
{
}
ARM_LIB_HEAP +0 EMPTY 0x10000
{
}
}
The ARM_LIB_STACK and ARM_LIB_HEAP regions are required because the program is being
linked with the semihosting libraries.
4. Compile and link the sources:
armcc -c -g function.c
armcc -c -g main.c
armlink --no_autoat --scatter=scatter.scat --map function.o main.o -o squared.axf
The --map option displays the memory map of the image.
The memory map shows that the variable is placed in the ER2 execution region at address
0x11000:
...
Execution Region ER2 (Base: 0x00001598, Size: 0x0000ea6c, Max: 0xffffffff, ABSOLUTE)
Base Addr Size Type Attr Idx E Section Name Object
0x00001598 0x0000000c Code RO 3 .text function.o
0x000015a4 0x0000ea5c PAD
0x00010000 0x00000004 Data RO 15 .ARM.__at_0x10000 main.o...
8.11.4 See also
In this example, the size of ER1 is uknown. Therefore, gValue might be placed in ER1 or ER2. To
make sure that gValue is placed in ER2, you must include the corresponding selector in ER2 and
link with the --no_autoat command-line option. If you omit --no_autoat, gValue is to placed in
a separate load region LR$$.ARM.__AT_0x00010000 that contains the execution region
ER$$.ARM.__AT_0x00020000.
Tasks
• Placing a named section explicitly using scatter-loading on page 8-23
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