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35 lines
1.5 KiB
Markdown
35 lines
1.5 KiB
Markdown
# Binary Size
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ELF files contain metadata like debug information so their size on disk is not a good indication of the amount of Flash the program will use once it's loaded on the target device's memory.
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To display the amount of Flash the program will occupy on the target device use the `cargo-size` tool, which is part of the `cargo-binutils` package.
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✅ Use the following command to print the binary's size in system V format.
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``` console
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$ cargo size --bin hello -- -A
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```
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Expected output:
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The breakdown of the program's static memory usage per *linker section*.
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``` console
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hello :
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section size addr
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.vector_table 256 0x0
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.text 9740 0x100
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.rodata 4568 0x270c
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.data 8 0x20000000
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.bss 2124 0x20000008
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.uninit 0 0x20000854
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```
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**🔎 More details about each linker section:**
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The first three sections are contiguously located in Flash memory -- Flash memory spans from address `0x0000_0000` to `0x0010_0000` (1 MB).
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* The `.vector_table` section contains the *vector table*, a data structure required by the Cortex-M ISA.
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* The `.text` section contains the instructions the program will execute.
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* The `.rodata` section contains constants like strings literals.
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The next three sections, `.data`, `.bss` and `.uninit`, are located in RAM -- RAM memory spans the address range `0x2000_0000` - `0x2004_0000` (256 KB). These sections contain statically allocated variables (`static` variables).
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