Date: Tue, 27 Mar 2018 08:20:24 +0200 From: Antoine Brodin <antoine@freebsd.org> To: Ed Maste <emaste@freebsd.org> Cc: FreeBSD Current <freebsd-current@freebsd.org>, "freebsd-toolchain@FreeBSD.org" <freebsd-toolchain@freebsd.org> Subject: Re: Heads-up: linker (lld) changes for amd64 coming soon Message-ID: <CAALwa8kfdg31-Vt=v78ZHV1Us9_%2BN01PC7cwiKFe81720Hguhw@mail.gmail.com> In-Reply-To: <CAPyFy2AjEJjryjgGCHAo107mkOUnFbKmkcMVFWQEKKbTEuu8AA@mail.gmail.com> References: <CAPyFy2AjEJjryjgGCHAo107mkOUnFbKmkcMVFWQEKKbTEuu8AA@mail.gmail.com>
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On Tue, Mar 27, 2018 at 4:14 AM, Ed Maste <emaste@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@) 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@ 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
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