ARM Compiler toolchain Using the Linker - ARM Information Center

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9.1 About GNU ld script support and restrictions GNU ld script support in armlink armlink supports the use of GNU ld scripts, but with some restrictions: • armlink implements a subset of the GNU ld script language • the subset is focused on support for ARM Linux and partial linking • Virtual Address (VMA) must equal Load Address (LMA) • bare-metal support is not supported in this release • the armlink --sysv command-line option uses an internal ld script. --sysv is also the default for the --arm_linux command-line option. You specify an ld script with the armlink --linker_script ld_script command-line option, or the synonym command-line option -T ld_script. 9.1.1 Using ld scripts when linking images and shared objects To link an image or shared object: • The --sysv or the --arm_linux option is are required. • Any unrecognized file is parsed as if it is an ld script. • All ELF images and shared objects produced by an ld script are demand paged. Use the --pagesize option to control the page size. The default is 0x8000. 9.1.2 Using ld scripts when linking partial objects 9.1.3 See also To link a partial object, you must use the armlink --ldpartial command-line option. The -r command-line option is a synonym for --ldpartial. Concepts • Typical use cases for using ld scripts with armlink on page 9-3 • Important ld script commands that are implemented in armlink on page 9-4 • Specific restrictions for using ld scripts with armlink on page 9-6 • Recommendations for using ld scripts with armlink on page 9-7 • Default GNU ld scripts used by armlink on page 9-8. Reference Linker Reference: • --arm_linux on page 2-13 • --ldpartial on page 2-94 • --linker_script=ld_script on page 2-100 • --pagesize=pagesize on page 2-118 • --sysroot=path on page 2-169 • --sysv on page 2-170. Other information • Using LD The GNU Linker. ARM DUI 0474C Copyright © 2010-2011 ARM. All rights reserved. 9-2 ID080411 Non-Confidential
9.2 Typical use cases for using ld scripts with armlink 9.2.1 See also The following are typical use cases for using ld scripts with armlink: GNU ld script support in armlink Wrapping libraries Some libraries have a dynamic and static part. An ld script loads both libraries in the correct order with the INPUT command, for example: INPUT(libstatic.a) INPUT(libdynamic.so) This script instructs the linker to load libstatic.a then libdynamic.so Partial linking with the --ldpartial option An ld script can be given to control how the linker combines sections, for example: SECTIONS { .text :0 { *(.text) *(mysection) } } This script instructs the linker to combine mysection and all the .text sections into a single .text output section. Fine control over an ARM linux link You might want to combine sections together in a different order to that given by the default linker script. Also, you might want the linker to define symbols at specific addresses. This information can be given by a custom linker script. Note To successfully produce a file that can be run on ARM Linux your image must include some output sections to contain the meta-data that the dynamic loader can use to load the file. It is recommended that you start with one of the example scripts and modify it to suit your purpose. Concepts • Example GNU ld script for linking an ARM Linux executable on page 9-12 • Example GNU ld script for linking an ARM Linux shared object on page 9-14 • Example GNU ld script for linking ld --ldpartial object on page 9-16. Reference Linker Reference: • --ldpartial on page 2-94 • --linker_script=ld_script on page 2-100 • --sysroot=path on page 2-169. ARM DUI 0474C Copyright © 2010-2011 ARM. All rights reserved. 9-3 ID080411 Non-Confidential
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® ARM Copyright © 2010-2011 ARM.
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Contents ARM Compiler toolchain Usi
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Contents 7.15 Creating a symdefs fi
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Chapter 1 Conventions and feedback
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Chapter 2 Overview of the linker Th
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Concepts • Demand paging on page
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2.3 Linker command-line options lis
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• --keep_protected_symbols on pag
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• --eager_load_debug, --no_eager_
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2.5 What the linker outputs 2.5.1 S
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Chapter 3 Linking models supported
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3.2 Bare-metal linking model 3.2.1
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Linking models supported by armlink
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3.5.1 See also • There are restri
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3.7 Concepts common to both BPABI a
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Image structure and generation •
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4.1.1 See also Image structure and
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4.3 Load view and execution view of
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4.4 Methods of specifying an image
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4.5 Types of simple image 4.5.1 See
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4.10 About specifying an initial en
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4.11.2 Example 4.11.3 See also The
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4.13 Section alignment with the lin
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Reference Linker Reference: • --a
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4.16 Overview of veneers 4.16.1 See
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4.18 Veneer types 4.18.1 See also I
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4.20 Reuse of veneers when scatter-
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4.22 About weak references and defi
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BL init_foo ;Rest of code END 4.22.
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Image structure and generation 4.24
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4.25 Specifying user libraries when
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4.27 Use of the strict family of op
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5.1 Elimination of common debug sec
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5.3 Elimination of unused sections
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5.4 Elimination of unused virtual f
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• --scatter=file on page 2-142. C
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5.6.1 See also Using linker optimiz
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3. Creates the output image. 5.7.3
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5.9 How the linker chooses a compre
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5.11 How compression is applied 5.1
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5.13 Inlining functions with the li
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Reference Assembler Reference: •
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5.16 About reordering of tail calli
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5.18 About merging comment sections
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6.1 Linker options for getting info
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6.3 Example of using the --info lin
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6.4 How to find where a symbol is p
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• Load$$LR$$ load region symbols
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7.2 Accessing linker-defined symbol
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7.4 Image$$ execution region symbol
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7.5.1 See also Accessing and managi
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7.7 Region name values when not sca
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7.9 Importing linker-defined symbol
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7.11 Section-related symbols 7.11.1
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7.13 Input section symbols 7.13.1 S
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7.15 Creating a symdefs file 7.15.1
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7.17 Reading a symdefs file 7.17.1
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7.18.2 See also 0x0000814D T __argv
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7.20 Specifying steering files on t
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7.22 Steering file format 7.22.1 Se
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7.24 Using $Super$$ and $Sub$$ to p
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Using scatter files • Images with
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8.2 When to use scatter-loading 8.2
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• --startup=symbol, --no_startup
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8.4.1 See also Concepts • About s
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8.5.1 See also } SRAM 0x8000 0x8000
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8.7 Specifying stack and heap using
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8.9 Creating root execution regions
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8.9.2 See also Tasks • Using the
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8.11 Placing functions and data at
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Page 149 and 150: Using scatter files • Using __at
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Page 157 and 158: Using scatter files 8.15 Example of
Page 159 and 160: 8.16 Examples of using sorting algo
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Page 239 and 240: 10.23 About symbol versioning 10.23
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11.2 Example scatter file for the B
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Features of the Base Platform linki
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Change Topics affected Revisions fo
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