ARM Compiler toolchain Using the Linker - ARM Information Center

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8.36 Using expression evaluation in a scatter file to avoid padding Using scatter files Using the ALIGN, ALIGNALL, or FIXED attributes in a scatter file can result in a large amount of padding in the image. To remove this padding, you can use expression evaluation to specify the start address of a load region and execution region. The built-in function AlignExpr is available to help you specify address expressions. 8.36.1 Example to avoid padding in scatter file 8.36.2 See also The following scatter file produces an image with padding: LR1 0x4000 { ER1 +0 ALIGN 0x8000 { ... } } Using the ALIGN keyword ER1 is aligned to a 0x8000 boundary in both the load and the execution view. To align in the load view, the linker must insert 0x4000 bytes of padding. The following scatter file produces an image without padding: LR1 0x4000 { ER1 AlignExpr(+0, 0x8000) { ... } } Using AlignExpr the result of +0 is aligned to a 0x8000 boundary. This creates an execution region with a load address of 0x4000 but an Execution Address of 0x8000. Concepts • Expression evaluation in scatter files on page 8-58. Linker Reference: • Example of aligning a base address in execution space but still tightly packed in load space on page 4-41. Reference Linker Reference: • Execution region attributes on page 4-11 • AlignExpr(expr, align) function on page 4-42. ARM DUI 0474C Copyright © 2010-2011 ARM. All rights reserved. 8-59 ID080411 Non-Confidential
8.37 Equivalent scatter-loading descriptions for simple images 8.37.1 See also Using scatter files The command-line options --reloc, --ro_base, --rw_base, --ropi, --rwpi, and --split create the simple image types: • Type 1 image, one load region and contiguous execution regions • Type 2 image, one load region and non-contiguous execution regions • Type 3 image, two load regions and non-contiguous execution regions. You can create the same image types by using the --scatter command-line option and a file containing one of the corresponding scatter-loading descriptions. Concepts • Types of simple image on page 4-10 • Type 1 image, one load region and contiguous execution regions on page 8-61 • Type 2 image, one load region and non-contiguous execution regions on page 8-63 • Type 3 image, two load regions and non-contiguous execution regions on page 8-65. Linker Reference: • About load region descriptions on page 4-5. Reference Linker Reference: • --reloc on page 2-132 • --ro_base=address on page 2-135 • --ropi on page 2-136 • --rw_base=address on page 2-139 • --rwpi on page 2-140 • --scatter=file on page 2-142 • --split on page 2-154 • Load region attributes on page 4-7. ARM DUI 0474C Copyright © 2010-2011 ARM. All rights reserved. 8-60 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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Page 141 and 142: 8.9 Creating root execution regions
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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 165 and 166: 8.20 Restrictions on placing __at s
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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 177 and 178: 8.29 Example of placing ARM C++ lib
Page 179 and 180: 8.31 Reserving an empty region Usin
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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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