linux-kernel - Re: [PATCH v4 4/5] MIPS: VDSO: Use $(LD) instead of $(CC) to link VDSO

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Date:   Sat, 2 May 2020 14:34:06 +0100 (BST)
From:   "Maciej W. Rozycki" <macro@...ux-mips.org>
To:     Fangrui Song <maskray@...gle.com>
cc:     Nathan Chancellor <natechancellor@...il.com>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Masahiro Yamada <masahiroy@...nel.org>,
        linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com, linux-kbuild@...r.kernel.org,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        Dmitry Golovin <dima@...ovin.in>,
        Sedat Dilek <sedat.dilek@...il.com>
Subject: Re: [PATCH v4 4/5] MIPS: VDSO: Use $(LD) instead of $(CC) to link
 VDSO

On Tue, 28 Apr 2020, Fangrui Song wrote:

> Sigh...  -G 0. This is an option ignored by LLD. GCC devs probably should
> have used the long option --gpsize rather than take the short option -G.
> Even better, -z gpsize= or similar if this option is specific to ELF.

 Well, the `-G' option is some 30 years old and comes from RISC-OS where 
the vendor linker had it; it was already present with the initial MIPS 
port of GCC:

commit fe3ec4f798ceea52e1b542b481670b83c12347fd
Author: Michael Meissner <meissner@....gnu.org>
Date:   Sun Dec 1 05:02:56 1991 +0000

    Initial revision

    From-SVN: r88

specifically:

+#define LINK_SPEC	"%{G*}						\

there, so I don't know of what GCC developers' choice you are talking 
about.

 Much of GCC legacy comes from various vendors' compilation systems; in 
this case it was the MIPS Computer Systems (aka MIPSCO) compiler.  There 
may not have been a GNU linker port to RISC-OS at that point (or ever), 
and the assembler and linker invocation interfaces were kept compatible as 
ports were added to individual GNU development tools, for obvious reasons.  
I still remember using GCC with vendor's assembler and linker on DEC 
Ultrix/MIPS myself many years ago, to overcome some vendor compiler's 
limitations.

 And FTR this was still a few years before ELF was even invented; MIPS OSs 
used the COFF binary format back then.

 Sorry.  I think it's LLVM/LLD that ignores compatibility, not the other 
way round.

  Maciej