Can't build kernel anymore: amd64 kernel requires linker ifunc support

[Oliver Pinter]

On 5/16/18, Rodney W. Grimes <freebsd-rwg at pdx.rh.cn85.dnsmgr.net> wrote:
>> On 16 May 2018 at 09:35, Rodney W. Grimes
>> <freebsd-rwg at pdx.rh.cn85.dnsmgr.net> wrote:
>> >>
>> >> LD=ld.lld make
>> >>
>> >> is the magic here. The kernel needs a new linker to properly link in
>> >> the
>> >> ifunc, and that's not our ancient ld. lld does it, as does the
>> >> latter-day
>> >> binutils.
>> >
>> > Since this now seems to be a mandatory thing to get a kernel built
>> > can it please be set in the Makefile that is needing it?
>>
>> It's already handled by the Makefile that needs it when using the
>> normal build process - i.e., "make buildworld buildkernel" (or
>> toolchain or kernel-toolchain followed by buildkernel).
>>
>> The failure arises when building a kernel the "old" way, using config
>> and then and make in the kernel directory. This inherently uses the
>> host's linker (/usr/bin/ld), which is too old to link the kernel. We
>> can't just add LD=ld.lld to the kernel's Makefile(s), because it would
>> break external toolchain and other cases where users use a specific
>> linker. I hope to introduce a KERNEL_LD Make variable that controls
>> the linker used for the kernel link, but it's more involved than a one
>> or two line change for the same reason that we can't just set
>> LD=ld.lld.
>>
>> ld.lld will start being installed as /usr/bin/ld once these two issues
>> are resolved:
> ...
>
> In the meantime what about reverting the ifunc usage until this
> can be done?

Nope. If somebody take trouble over compiling their kernel manually,
then at least
read the documentation, how to compile their system in the new way.
We talking about 12-CURRENT and not about 1X-STABLE branches....

>
>>
>> pr227968 [exp-run] Update lang/ghc to 8.4.2, devel/stack to 1.7.1, and
>> all the */hs-* ports
>> pr214864 [exp-run] test build with lld as /usr/bin/ld
>>
>> The exp-run for the first is complete and I believe we are now just
>> waiting on the change to be committed. As soon as that happens I will
>> ask for another exp-run for the second PR, and will commit the change
>> to install lld by default as soon as it completes (assuming
>> successfully).
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>
> --
> Rod Grimes
> rgrimes at freebsd.org
>