ARM Compiler toolchain Using the Linker - ARM Information Center

8.9 Creating root execution regions
To specify a region as a root region in a scatter file you can:
Using scatter files
• Specify ABSOLUTE as the attribute for the execution region, either explicitly or by
permitting it to default, and use the same address for the first execution region and the
enclosing load region. To make the execution region address the same as the load region
address, either:
— Specify the same numeric value for both the base address for the execution region
and the base address for the load region.
— Specify a +0 offset for the first execution region in the load region.
If an offset of zero (+0) is specified for all subsequent execution regions in the load
region, then all execution regions not following an execution region containing ZI
are also root regions.
The following example shows an implicitly defined root region:
Example 8-4 Implicit root region with the same load and execution address
LR_1 0x040000 ; load region starts at 0x40000
{ ; start of execution region descriptions
ER_RO 0x040000 ; load address = execution address
{
* (+RO) ; all RO sections (must include section with
; initial entry point)
}
... ; rest of scatter-loading description
}
• Use the FIXED execution region attribute to ensure that the load address and execution
address of a specific region are the same.
You can use the FIXED attribute to place any execution region at a specific address in ROM.
For example, the following memory map shows fixed execution regions:
Single
load
region
init.o
Empty
*(RO)
Load view
Filled with zeroes or the value defined using
the --pad option
0x80000
0x4000
Execution view
Figure 8-3 Memory map for fixed execution regions
The following example shows the corresponding scatter-loading description:
ARM DUI 0474C Copyright © 2010-2011 ARM. All rights reserved. 8-14
ID080411 Non-Confidential
init.o
*(RO)
(FIXED)
(movable)