Date: Wed, 16 May 2018 13:46:43 -0600 From: Warner Losh <imp@bsdimp.com> To: Oliver Pinter <oliver.pinter@hardenedbsd.org> Cc: "Rodney W. Grimes" <freebsd-rwg@pdx.rh.cn85.dnsmgr.net>, Hans Petter Selasky <hps@selasky.org>, Emeric POUPON <emeric.poupon@stormshield.eu>, Ed Maste <emaste@freebsd.org>, freebsd-arch <freebsd-arch@freebsd.org> Subject: Re: Can't build kernel anymore: amd64 kernel requires linker ifunc support Message-ID: <CANCZdfp_GYSazyPJYhrBcbsvrJ989HD52OfoTfMn9eNCmbXHDA@mail.gmail.com> In-Reply-To: <CAPQ4fftHqK1KvrMi1Vbkuh_p5ZDRSz6eNJQX3QUJPsgmNSJ9nA@mail.gmail.com> References: <CAPyFy2A-aWa5oKukOKWeAN3BCB07nXzLbO%2B_Txp5HHk0C0h9_g@mail.gmail.com> <201805161511.w4GFBCTQ001108@pdx.rh.CN85.dnsmgr.net> <CAPQ4fftHqK1KvrMi1Vbkuh_p5ZDRSz6eNJQX3QUJPsgmNSJ9nA@mail.gmail.com>
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On Wed, May 16, 2018 at 1:34 PM, Oliver Pinter < oliver.pinter@hardenedbsd.org> wrote: > On 5/16/18, Rodney W. Grimes <freebsd-rwg@pdx.rh.cn85.dnsmgr.net> wrote: > >> On 16 May 2018 at 09:35, Rodney W. Grimes > >> <freebsd-rwg@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.... IMHO, this is an acceptable breakage for -current. This is on the 'experts only' path and there's a note in UPDATING to cope. We don't intend to keep it that way forever, and the benefit of getting useful testing from a wider audience in this case, imho, out weights the minor inconvenience for the small minority of users that go old-school. Warner
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