Differences

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--- lld [2019/01/09 13:51] – VIMAGE issues sorted out EdMaste
+++ lld [2022/02/10 03:13] (current) – Add Category: Project KubilayKocak
@@ Line 1: / Line 1: @@
-====== Background ======
+====== Introduction ======
-lld, part of the LLVM family of projects, is a high-performance linker for the ELF, COFF, and Mach-O object formats. This page describes the ongoing project to use lld as %%FreeBSD%%'s base system linker.
-===== In-tree LLD =====
+[[https://lld.llvm.org/|lld]], part of the LLVM family of projects, is a high-performance linker for the ELF, COFF, and Mach-O object formats. This page describes the now-completed project to use lld as %%FreeBSD%%'s base system linker.
-%%FreeBSD%%-CURRENT contains LLD 7.0.1. LLD is currently the default system linker on amd64, arm*, and aarch64. On i386 LLD is ''%%/usr/bin/ld.lld%%'' but ''%%/usr/bin/ld%%'' is still GNU BFD ld.
+===== LLD in Base =====
-On other architectures, to build world and kernel with LLD and install LLD as /usr/bin/ld, add to /etc/src.conf:
+As of 13, lld is now the default system linker on all supported architectures.
+Prior to this, lld was in use on i386, amd64, arm*, aarch64, and riscv64*, with other architectures still using GNU BFD ld. For more information, see arch(7) in the manual for your particular %%FreeBSD%% version.
+To forcibly build world and kernel with LLD and install LLD as /usr/bin/ld in pre-13 versions, add to /etc/src.conf:
 <code>
@@ Line 15: / Line 18: @@
 ''%%WITH_LLD_BOOTSTRAP=yes%%'' uses lld as the linker for building the %%FreeBSD%% world, and has no effect on the linker installed in ''%%/usr/bin/ld%%''. ''%%WITH_LLD_IS_LD=yes%%'' installes lld as ''%%/usr/bin/ld%%'', and has no effect on the linker used for building world.
-===== Upstream LLD =====
+====== Historical Issues ======
-==== Build upstream lld ====
+===== LLD patches =====
-<code>
-git clone https://github.com/llvm-mirror/llvm
-cd llvm/tools
-git clone https://github.com/llvm-mirror/lld
-mkdir ../build && cd ../build
-cmake -G "Unix Makefiles" ../
-make -j8
-</code>
-==== Make lld the default linker ====
-<code>
-cd build/bin
-ln -s lld ld
-setenv PATH /path/to/llvm/build/bin:$PATH
-setenv LD /path/to/llvm/build/bin
-rehash
-</code>
-To check if the changes took effect:
-<code>
-davide@rabbit1:/home/davide/llvm/build/bin $ ld --help | head -n 1
-OVERVIEW: LLVM Linker
-</code>
-====== Per-arch status (in HEAD) ======
-^ Architecture ^ World ^ Kernel ^ Bootstrap linker ^ /usr/bin/ld ^
-| amd64 | OK | OK | lld | lld |
-| arm64 | OK | OK | lld | lld |
-| i386 | OK | OK | lld | bfd |
-| arm | libc fails to link | LLD targets v7l+ | bfd | bfd |
-| armv6 | libc fails to link | LLD targets v7l+ | bfd | bfd |
-| armv7 | OK | OK | lld | bfd |
-| mips64 | Most links, untested | Link fails | bfd | bfd |
-| mips | Most links, untested | Link fails | bfd | bfd |
-| powerpc64 | libc fails to link | Untested | bfd | bfd |
-| powerpc | libc fails to link | Untested | bfd | bfd |
-| sparc64 | no support | no support | bfd | bfd |
-| riscv | no support | no support | bfd | bfd |
-====== TODO ======
-===== WIP patches =====
-==== lld ====
   * <del>[[https://reviews.llvm.org/D41037|Create reserved symbols early so they can be versioned]]</del>
@@ Line 75: / Line 32: @@
   * <del>[[https://reviews.llvm.org/D34692|Add support for multiple passes to createThunks]] (2017-06-27)</del>
-==== FreeBSD ====
+===== Ports =====
-====== Known Issues ======
 A %%FreeBSD%% ports exp-run is tracked in [[https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=214864|PR214864]].
@@ Line 83: / Line 39: @@
   * print/gl2ps needs explicit -L/usr/lib [[https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=218399|PR218399]].
-===== Common issues in ports =====
+Common issues in ports:
   - Passing compiler flags, such as ''%%-fPIC%%'', to the linker.
   - lld has no built-in search paths (''%%/lib, /usr/lib%%''). Normally the linker is invoked from the compiler driver, which adds the library search paths. If lld is invoked directly then library search paths must be explicitly specified, with ''%%-L/lib -L/usr/lib%%''.
@@ Line 89: / Line 46: @@
   - lld does not have a built-in default output target. For the most common use of the linker (linking individual .o objects in to an executable or shared object) lld infers the target from the first object file. However, when the linker is used to convert an arbitrary binary file into an ELF object (via -r -b binary) lld must have the output target specified explicitly with -m.
-====== Links ======
+====== Resources ======
   * Rui Ueyama's [[https://www.youtube.com/watch?v=CYCRqjVa6l4|New LLD linker for ELF]] talk
   * [[http://lists.llvm.org/pipermail/llvm-dev/2016-March/096449.html|Linking the FreeBSD base system with LLD]] status update from March 2016
   * [[https://docs.google.com/document/d/1GcTY7kDKmvSYFAkJdUjLbHwoMHZlpbGG49wdWuaEnrg/edit?usp=sharing|lld as the FreeBSD base system linker]] Google Doc
+----
+{{tag>Historical}}
+{{tag>Project}}