ARM Compiler toolchain Using the Linker - ARM Information Center

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8.18 Using __attribute__((section("name"))) 8.18.1 See also Using scatter files You can place code and data by separating them into their own objects without having to use toolchain-specific pragmas or attributes. However, you can also use __attribute__((section("name"))) to place an item in a separate ELF section. You can then use a scatter file to place the named sections at specific locations. To use __attribute__((section("name"))) to place a variable in a separate section: 1. Use __attribute__((section("name"))) to specify the named section where the variable is to be placed, for example: int variable __attribute__((section("foo"))) = 10; 2. Use a scatter file to place the named section, for example: FLASH 0x24000000 0x4000000 { ... ; rest of code } ADDER 0x08000000 { file.o (foo) ; select section foo from file.o } Be aware of the following: • linking with --autoat or --no_autoat does not affect the placement Example 8-8 Naming a section Example 8-9 Placing a section • if scatter-loading is not used, the section is placed in the default ER_RW execution region of the LR_1 load region • if you have a scatter file that does not include the foo selector, then the section is placed in the defined RW execution region. You can also place a function at a specific address using .ARM.__at_address as the section name. For example, to place the function sqr at 0x20000, specify: int sqr(int n1) __attribute__((section(".ARM.__at_0x20000"))); int sqr(int n1) { return n1*n1; } Reference • Using __at sections to place sections at a specific address on page 8-37 • Restrictions on placing __at sections on page 8-38. ARM DUI 0474C Copyright © 2010-2011 ARM. All rights reserved. 8-35 ID080411 Non-Confidential
Compiler Reference: • __attribute__((section("name"))) function attribute on page 5-53 • #pragma arm section [section_type_list] on page 5-83. Linker Reference: • --autoat, --no_autoat on page 2-17 • --scatter=file on page 2-142. Using scatter files ARM DUI 0474C Copyright © 2010-2011 ARM. All rights reserved. 8-36 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$$ execution region symbol
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7.5.1 See also Accessing and managi
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7.7 Region name values when not sca
Page 111 and 112: 7.9 Importing linker-defined symbol
Page 113 and 114: 7.11 Section-related symbols 7.11.1
Page 115 and 116: 7.13 Input section symbols 7.13.1 S
Page 117 and 118: 7.15 Creating a symdefs file 7.15.1
Page 119 and 120: 7.17 Reading a symdefs file 7.17.1
Page 121 and 122: 7.18.2 See also 0x0000814D T __argv
Page 123 and 124: 7.20 Specifying steering files on t
Page 125 and 126: 7.22 Steering file format 7.22.1 Se
Page 127 and 128: 7.24 Using $Super$$ and $Sub$$ to p
Page 129 and 130: Using scatter files • Images with
Page 131 and 132: 8.2 When to use scatter-loading 8.2
Page 133 and 134: • --startup=symbol, --no_startup
Page 135 and 136: 8.4.1 See also Concepts • About s
Page 137 and 138: 8.5.1 See also } SRAM 0x8000 0x8000
Page 139 and 140: 8.7 Specifying stack and heap using
Page 141 and 142: 8.9 Creating root execution regions
Page 143 and 144: 8.9.2 See also Tasks • Using the
Page 145 and 146: 8.11 Placing functions and data at
Page 147 and 148: Using scatter files RAM 0x200000 (0
Page 149 and 150: Using scatter files • Using __at
Page 151 and 152: Developing Software for ARM ® Proc
Page 153 and 154: } } .ANY1(+RO) ; evenly distributed
Page 155 and 156: 8.14 Examples of using placement al
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 165 and 166: 8.20 Restrictions on placing __at s
Page 167 and 168: 8.21.1 See also Using scatter files
Page 169 and 170: 8.23 Placing a key in flash memory
Page 171 and 172: 8.25 Placement of sections with ove
Page 173 and 174: 8.25.1 See also Using scatter files
Page 175 and 176: 8.27 Example of placing code in a r
Page 177 and 178: 8.29 Example of placing ARM C++ lib
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
Page 195 and 196: Using scatter files Example 8-29 Sc
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 and 202: Reference Linker Reference: • --l
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Page 209 and 210: 9.7.1 See also } .dynamic : { *(.dy
Page 211 and 212: 9.8.1 See also { *(.bss .bss.*) . =
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Chapter 10 BPABI and SysV shared li
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BPABI and SysV shared libraries and
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10.3 Concepts common to all BPABI m
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10.5 Symbol visibility for BPABI mo
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10.6 Automatic import and export fo
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10.8 Symbol versioning for BPABI mo
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10.10 Linker options for SysV model
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10.13 Addressing modes in the SysV
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10.17 Linker options for bare metal
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10.21 Addressing modes in the BPABI
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10.23 About symbol versioning 10.23
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10.25 Example of creating versioned
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10.27 Linker options for enabling i
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Chapter 11 Features of the Base Pla
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Features of the Base Platform linki
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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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