75 lines
3.8 KiB
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75 lines
3.8 KiB
HTML
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<title>Nios II - Untitled</title>
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<!--
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This file documents the GNU linker LD
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(GNU Toolchain for the A-profile Architecture 9.2-2019.12 (arm-9.10))
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version 2.33.1.
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Copyright (C) 1991-2019 Free Software Foundation, Inc.
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<a name="Nios-II"></a>
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Next: <a rel="next" accesskey="n" href="PowerPC-ELF32.html#PowerPC-ELF32">PowerPC ELF32</a>,
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Previous: <a rel="previous" accesskey="p" href="NDS32.html#NDS32">NDS32</a>,
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Up: <a rel="up" accesskey="u" href="Machine-Dependent.html#Machine-Dependent">Machine Dependent</a>
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<h3 class="section">4.10 <samp><span class="command">ld</span></samp> and the Altera Nios II</h3>
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<p><a name="index-Nios-II-call-relaxation-700"></a><a name="index-g_t_002d_002drelax-on-Nios-II-701"></a>
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Call and immediate jump instructions on Nios II processors are limited to
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transferring control to addresses in the same 256MB memory segment,
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which may result in <samp><span class="command">ld</span></samp> giving
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‘<samp><span class="samp">relocation truncated to fit</span></samp>’ errors with very large programs.
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The command-line option <samp><span class="option">--relax</span></samp> enables the generation of
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trampolines that can access the entire 32-bit address space for calls
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outside the normal <code>call</code> and <code>jmpi</code> address range. These
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trampolines are inserted at section boundaries, so may not themselves
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be reachable if an input section and its associated call trampolines are
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larger than 256MB.
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<p>The <samp><span class="option">--relax</span></samp> option is enabled by default unless <samp><span class="option">-r</span></samp>
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is also specified. You can disable trampoline generation by using the
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<samp><span class="option">--no-relax</span></samp> linker option. You can also disable this optimization
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locally by using the ‘<samp><span class="samp">set .noat</span></samp>’ directive in assembly-language
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source files, as the linker-inserted trampolines use the <code>at</code>
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register as a temporary.
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<p>Note that the linker <samp><span class="option">--relax</span></samp> option is independent of assembler
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relaxation options, and that using the GNU assembler's <samp><span class="option">-relax-all</span></samp>
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option interferes with the linker's more selective call instruction relaxation.
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</body></html>
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