ARM Compiler toolchain Using the Linker - ARM Information Center

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8.41 Scatter file to ELF mapping For simple images, ELF executable files contain segments: Using scatter files • a load region is represented by an ELF Program Segment with type PT_LOAD • an execution region is represented by up to three ELF Sections: — one for RO — one for RW — one for ZI. For example, you might have a scatter file similar to the following: LOAD 0x8000 { EXEC_ROM +0 { *(+RO) } RAM +0 { *(+RW,+ZI) } HEAP +0x100 EMPTY 0x100 { } STACK +0 EMPTY 0x400 { } } Example 8-28 Scatter file This scatter file creates a single Program Segment with type PT_LOAD for the load region with address 0x8000. A single Output Section with type SHT_PROGBITS is created to represent the contents of EXEC_ROM. Two Output Sections are created to represent RAM. The first has a type SHT_PROGBITS and contains the initialized read/write data. The second has a type of SHT_NOBITS and describes the zero-initialized data. The heap and stack are described in the ELF file by SHT_NOBITS sections. Enter the following fromelf command to see the scatter-loaded sections in the image: fromelf --text -v my_image.axf To display the symbol table, enter the command: fromelf --text -s -v my_image.axf The following is an example of the fromelf output showing the LOAD, EXEC_ROM, RAM, HEAP, and STACK sections: ARM DUI 0474C Copyright © 2010-2011 ARM. All rights reserved. 8-67 ID080411 Non-Confidential
Using scatter files Example 8-29 Scatter-loaded sections in the ELF image ... ======================================================================== ** Program header #0 Type : PT_LOAD (1) File Offset : 52 (0x34) Virtual Addr : 0x00008000 Physical Addr : 0x00008000 Size in file : 764 bytes (0x2fc) Size in memory: 2140 bytes (0x85c) Flags : PF_X + PF_W + PF_R + PF_ARM_ENTRY (0x80000007) Alignment : 4 ======================================================================== ** Section #1 Name : EXEC_ROM ... Addr : 0x00008000 File Offset : 52 (0x34) Size : 740 bytes (0x2e4) ... ==================================== ** Section #2 Name : RAM ... Addr : 0x000082e4 File Offset : 792 (0x318) Size : 20 bytes (0x14) ... ==================================== ** Section #3 Name : RAM ... Addr : 0x000082f8 File Offset : 812 (0x32c) Size : 96 bytes (0x60) ... ==================================== ** Section #4 Name : HEAP ... Addr : 0x00008458 File Offset : 812 (0x32c) Size : 256 bytes (0x100) ... ==================================== ** Section #5 Name : STACK ... Addr : 0x00008558 ARM DUI 0474C Copyright © 2010-2011 ARM. All rights reserved. 8-68 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
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
Page 161 and 162: 8.17 Selecting veneer input section
Page 163 and 164: Compiler Reference: • __attribute
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
Page 183 and 184: 8.33 Overalignment of execution reg
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: Using scatter files • The ER_ZI e
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
Page 203 and 204: 9.5 Recommendations for using ld sc
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Page 209 and 210: 9.7.1 See also } .dynamic : { *(.dy
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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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