Re: HEADS-UP: Linker issues building amd64 kernels with config & make

Ed Maste wrote:
> As of r333461 the amd64 kernel makes use of ifuncs, and requires
> support in the linker. A safety belt added in r333470 enforces this,
> and will produce an explicit error if the linker does not support
> ifuncs.
> 
> lld is the default bootstrap linker for amd64 and has ifunc support.
> The typical 'make buildworld' (or kernel-toolchain) followed by 'make
> buildkernel' process will use lld and successfully link a working
> kernel.
> 
> The old-style kernel build (using 'config' followed by a 'make' in the
> kernel directory) uses the host linker (/usr/bin/ld). This still
> defaults to GNU ld 2.17.50, which does not support ifuncs. This can be
> worked around in one of two ways:
> 
> 1. Install lld as the system linker (/usr/bin/ld), by adding
> WITH_LLD_IS_LD to /etc/src.conf and building and install world.
> WITH_LLD_IS_LD will become the default on amd64 in the near future -
> I'm just waiting on updates to the lang/ghc port and another exp-run.
> 
> 2. Override LD when you build the kernel:
> $ LD=ld.lld make
> 
> These tool chain components will undergo additional changes for the next while.

I guess this explains :
Date: Sun, 13 May 2018 20:26:38 +0200
Subject: cd /sys/amd64/compile/GENERIC;make cleandepend; make cleandepend
	.svn_revision 333575
	linking kernel.full
	iflib.o:(.rodata+0x178): undefined reference to `noop_attach'
	iflib.o:(.rodata+0x188): undefined reference to `iflib_pseudo_detach'

PS Bloat factor > 20: 2M static V 40M dynamic, 
(normaly dynamics are smaller, not larger).
	cd /usr/bin; ls -l *ld*
	-r-xr-xr-x  2 root  wheel   1935992 May 13 12:48 ld*
	-r-xr-xr-x  1 root  wheel  40449288 May 13 12:54 ld.lld*
	file ld ld.lld
	ld:     ELF 64-bit LSB executable, x86-64, version 1 (FreeBSD),
		 statically linked,
		 for FreeBSD 12.0 (1200063), FreeBSD-style, stripped
	ld.lld: ELF 64-bit LSB executable, x86-64, version 1 (FreeBSD),
		 dynamically linked, interpreter /libexec/ld-elf.so.1,
		 for FreeBSD 12.0 (1200063), FreeBSD-style, stripped

Cheers,
Julian
-- 
Julian Stacey, Computer Consultant, Systems Engineer, BSD Linux Unix, Munich
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