Re: Heads-up: linker (lld) changes for amd64 coming soon

On Tue, Mar 27, 2018 at 4:14 AM, Ed Maste <emaste_at_freebsd.org> wrote:
> Some changes related to the amd64 linker are nearly ready to be
> committed (within a week or three), so I'm sending this notice to
> request any final comments or concerns before these changes are made.
>
> 1. Kostik (kib_at_) has a patch to start using kernel ifunc, with the
> first use being Supervisor Mode Access Prevention (SMAP) on amd64.
> This relies on linker support that is available in the in-tree lld and
> in contemporary binutils ld.bfd from ports, but not in the in-tree
> ld.bfd 2.17.50.
>
> Right now we use lld as the default bootstrap linker for amd64 in
> -CURRENT -- that is, the kernel, and userland libraries and binaries
> are linked with lld. To revert to ld.bfd for amd64 the build-time knob
> WITHOUT_LLD_BOOTSTRAP=yes can currently be added to src.conf. When the
> ifunc changes get committed WITHOUT_LLD_BOOTSTRAP=yes will not work
> for amd64 kernels (and will be added to BROKEN_OPTIONS).
>
> 2. WITH_LLD_IS_LD controls whether /usr/bin/ld is ld.bfd or ld.lld,
> and thus the linker used for linking ports. I plan to switch this to
> default on.
>
> Most ports build just fine when lld is the system linker, but a few
> encounter trouble: some of the ports rely on options not supported by
> lld, rely on specific quirks of ld.bfd's implementation, or have a
> buggy linker invocation that is silently ignored by ld.bfd.
>
> The majority of such ports have now been adapted to work with lld or
> configured to use ld.bfd as the linker, but there are a small number
> of failing ports that do not provide a way to use other than the
> default system linker /usr/bin/ld. The outstanding issues can be found
> in the ports exp-run for lld as /usr/bin/ld, PR214864.
>
> Please follow up if you have any concerns or comments about these
> upcoming changes.

Hi,

I have no concerns about 1.
About 2.,  I am concerned that changes breaking a large number of
ports are committed without portmgr_at_ approval.
If WITH_LLD_IS_LD is committed as is on amd64,  packages for head
won't be published as it doesn't meet our current criteria for
publication.

Antoine