ARM Compiler toolchain Using the Linker - ARM Information Center

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9.4 Specific restrictions for using ld scripts with armlink 9.4.1 See also The following restrictions apply when using ld scripts with armlink: GNU ld script support in armlink PHDRS This command is not implemented. When using an ld script the linker always generates program headers automatically. MEMORY This command is not implemented. The linker assumes that it has a uniform memory space from 0 to 0XFFFFFFFF. OVERLAY This command is not implemented. Overlays are not permitted. Other commands and built-in functions The following commands and built-in functions are not supported: • ASSERT • FORCE_COMMON_ALLOCATION • INHIBIT_COMMON_ALLOCATION • INSERT AFTER • INSERT BEFORE • LENGTH • NOCROSSREFS • ORIGIN • REGION_ALIAS • TARGET armlink linker-defined symbols Each output section is defined internally as an execution region. The existing armlink execution region symbols can be used, for example: .text : { *(.text) } The output section .text is represented by an execution region called .text. You can use the symbol Image$$.text$$Base as if the execution region had been defined by a scatter file. Other restrictions Other restrictions are: • __AT sections are not supported when using ld scripts • RW compression is not supported when using ld scripts. Concepts • About GNU ld script support and restrictions on page 9-2 • Important ld script commands that are implemented in armlink on page 9-4 • Image$$ execution region symbols on page 7-6. Reference Linker Reference: • --linker_script=ld_script on page 2-100 • --symver_script=file on page 2-167. ARM DUI 0474C Copyright © 2010-2011 ARM. All rights reserved. 9-6 ID080411 Non-Confidential
9.5 Recommendations for using ld scripts with armlink GNU ld script support in armlink Follow these recommendations when producing ld scripts for use with armlink: 9.5.1 Recommendations for producing ld scripts for ARM Linux 9.5.2 General recommendations 9.5.3 See also The dynamic loader requires some output sections with a specific type to work properly. These are: • Hash Table • String Table • Dynamic Symbol Table • Dynamic Section • Version Sections • Thread Local Storage Sections. The following are general recommendations: • Make sure each output section has a homogenous type. For example: .text : { *(.text) } .data : { *(.data) } .bss : { *(.bss) } This is preferred to the following: .stuff { *(.text) *(.data) *(.bss) } • If you are running the ELF file on ARM Linux do not modify the location of the meta-data used by the dynamic linker. • Sections not matched by the SECTIONS command are marked as orphans. The linker places orphan sections in appropriate locations. The linker attempts to match the placement of orphans used by ld although this is not always possible. Use explicit placement if you do not like how armlink places orphans. Concepts • About GNU ld script support and restrictions on page 9-2 • 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. Reference Linker Reference: • --linker_script=ld_script on page 2-100 • --symver_script=file on page 2-167. ARM DUI 0474C Copyright © 2010-2011 ARM. All rights reserved. 9-7 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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Using scatter files RAM 0x200000 (0
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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 169 and 170: 8.23 Placing a key in flash memory
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Page 173 and 174: 8.25.1 See also Using scatter files
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Page 179 and 180: 8.31 Reserving an empty region Usin
Page 181 and 182: 8.32 About creating regions on page
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Page 185 and 186: 8.35 Expression evaluation in scatt
Page 187 and 188: 8.37 Equivalent scatter-loading des
Page 189 and 190: Using scatter files Example 8-23 Po
Page 191 and 192: Using scatter files Example 8-25 Po
Page 193 and 194: Using scatter files • The ER_ZI e
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Page 197 and 198: Chapter 9 GNU ld script support in
Page 199 and 200: 9.2 Typical use cases for using ld
Page 201: Reference Linker Reference: • --l
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Page 209 and 210: 9.7.1 See also } .dynamic : { *(.dy
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Page 237 and 238: 10.21 Addressing modes in the BPABI
Page 239 and 240: 10.23 About symbol versioning 10.23
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Page 245 and 246: Chapter 11 Features of the Base Pla
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Page 249 and 250: 11.2 Example scatter file for the B
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