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Linker User Guide
Conventions and feedback
Overview of the linker
Linking models supported by armlink
Image structure and generation
The image structure
Input sections, output sections, regions, and Prog
Load view and execution view of an image
Methods of specifying an image memory map with the
Types of simple image
Type 1 image, one load region and contiguous execu
Type 2 image, one load region and non-contiguous e
Type 3 image, two load regions and non-contiguous
Image entry points
About specifying an initial entry point
Section placement with the linker
Placing sections with FIRST and LAST attributes
Section alignment with the linker
Demand paging
About ordering execution regions containing Thumb
Overview of veneers
Veneer sharing
Veneer types
Generation of position independent to absolute ven
Reuse of veneers when scatter-loading
Using command-line options to control the generati
About weak references and definitions
How the linker performs library searching, selecti
Controlling how the linker searches for the ARM st
Specifying user libraries when linking
How the linker resolves references
Use of the strict family of options in the linker
Using linker optimizations
Getting information about images
Accessing and managing symbols with armlink
Using scatter files
Linker User Guide
The image structure
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| Home > Image structure and generation > The image structure | |||
The structure of an image is defined by the:
number of its constituent regions and output sections
positions in memory of these regions and sections when the image is loaded
positions in memory of these regions and sections when the image executes.
Each link stage has a different view of the image:
- ELF object file view (linker input)
The ELF object file view comprises input sections. The ELF object file can be:
a relocatable file that holds code and data suitable for linking with other object files to create an executable file
an executable file that holds a program suitable for execution.
- Linker view
The linker has two views for the address space of a program that become distinct in the presence of overlaid, position-independent, and relocatable program fragments (code or data):
The load address of a program fragment is the target address that the linker expects an external agent such as a program loader, dynamic linker, or debugger to copy the fragment from the ELF file. This might not be the address at which the fragment executes.
The execution address of a program fragment is the target address where the linker expects the fragment to reside whenever it participates in the execution of the program.
If a fragment is position-independent or relocatable, its execution address can vary during execution.
- ELF image file view (linker output)
The ELF image file view comprises Program Segments and output sections:
a load region corresponds to a Program Segment
an execution region corresponds to up to three output sections:
RO section
RW section
ZI section.
One or more execution regions make up a load region.
Note
With armlink, the maximum size of a Program Segment is 2GB.
When describing a memory view:
the term root region is used to describe a region that has the same load and execution addresses
load regions are equivalent to ELF segments.
The following figure shows the relationship between the views at each link stage:
See also| Copyright © 2007-2008, 2011-2012 ARM. All rights reserved. | ARM DUI 0377D |
| Non-Confidential | ID062912 |
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| Home > Image structure and generation > The image structure |
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