[llvm-dev] Default linker script used by lld
jingduanyang via llvm-dev
Hi,
Does anyone know the default linker script used by lld? This might be a silly question but I googled everywhere and couldn’t find an answer…
Thanks,
Duanyang
Peter Smith via llvm-dev
LLD, doesn’t have a built-in linker script in the same way as GNU ld.bfd does.
Input Sections are mapped to OutputSections via a simple function https://github.com/llvm/llvm-project/blob/main/lld/ELF/Writer.cpp#L98 then sections are sorted according to rank in https://github.com/llvm/llvm-project/blob/main/lld/ELF/Writer.cpp#L98 hopefully the comments in those files will help reverse engineer a script that looks similar.
In practice the default linker behaviour will most significantly differ from ld.bfd by sorting ro-data before ro-code rather than after. This tends towards 3 PT_LOAD program headers ro, ro+exec, rw.
Hope that helps
Peter
Fāng-ruì Sòng via llvm-dev
<llvm...@lists.llvm.org> wrote:
>
> LLD, doesn’t have a built-in linker script in the same way as GNU ld.bfd does.
>
>
>
> Input Sections are mapped to OutputSections via a simple function https://github.com/llvm/llvm-project/blob/main/lld/ELF/Writer.cpp#L98 then sections are sorted according to rank in https://github.com/llvm/llvm-project/blob/main/lld/ELF/Writer.cpp#L98 hopefully the comments in those files will help reverse engineer a script that looks similar.
>
>
>
> In practice the default linker behaviour will most significantly differ from ld.bfd by sorting ro-data before ro-code rather than after. This tends towards 3 PT_LOAD program headers ro, ro+exec, rw.
>
>
>
> Hope that helps
>
>
>
> Peter
I noted down some linker script differences in
https://maskray.me/blog/2020-12-19-lld-and-gnu-linker-incompatibilities
There was a feature request about dumping an internal linker script
https://bugs.llvm.org/show_bug.cgi?id=51309 but it would significantly
increase complexity without justifiable benefit. In addition, some
built-in processing cannot be serialized into a linker script. So I
closed it :)
>
>
> From: llvm-dev <llvm-dev...@lists.llvm.org> On Behalf Of jingduanyang via llvm-dev
> Sent: 25 October 2021 12:54
> To: llvm...@lists.llvm.org
> Cc: Weiwei (weiwei, Compiler) <weiw...@huawei.com>; Zhangwen(Esan) <zwzhangw...@huawei.com>
> Subject: [llvm-dev] Default linker script used by lld
>
>
>
> Hi,
>
>
>
> Does anyone know the default linker script used by lld? This might be a silly question but I googled everywhere and couldn’t find an answer…
>
>
>
> Thanks,
>
> Duanyang
>
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