ARM Compiler toolchain Using the Linker - ARM Information Center

8.36 Using expression evaluation in a scatter file to avoid padding
Using scatter files
Using the ALIGN, ALIGNALL, or FIXED attributes in a scatter file can result in a large amount of
padding in the image. To remove this padding, you can use expression evaluation to specify the
start address of a load region and execution region. The built-in function AlignExpr is available
to help you specify address expressions.
8.36.1 Example to avoid padding in scatter file
8.36.2 See also
The following scatter file produces an image with padding:
LR1 0x4000
{
ER1 +0 ALIGN 0x8000
{
...
}
}
Using the ALIGN keyword ER1 is aligned to a 0x8000 boundary in both the load and the execution
view. To align in the load view, the linker must insert 0x4000 bytes of padding.
The following scatter file produces an image without padding:
LR1 0x4000
{
ER1 AlignExpr(+0, 0x8000)
{
...
}
}
Using AlignExpr the result of +0 is aligned to a 0x8000 boundary. This creates an execution region
with a load address of 0x4000 but an Execution Address of 0x8000.
Concepts
• Expression evaluation in scatter files on page 8-58.
Linker Reference:
• Example of aligning a base address in execution space but still tightly packed in load
space on page 4-41.
Reference
Linker Reference:
• Execution region attributes on page 4-11
• AlignExpr(expr, align) function on page 4-42.
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