Date: Thu, 3 Dec 2015 15:35:12 -0600 From: Justin Hibbits <jrh29@alumni.cwru.edu> To: Ian Lepore <ian@freebsd.org> Cc: Warner Losh <imp@bsdimp.com>, Ed Maste <emaste@freebsd.org>, "freebsd-arch@freebsd.org" <freebsd-arch@freebsd.org> Subject: Re: Removing build metadata, for reproducible kernel builds Message-ID: <CAHSQbTBTefh6dfcn%2B0nUfjyMvtVuimzocPrnPDTkY1nXU7y9Ww@mail.gmail.com> In-Reply-To: <1449177325.6214.14.camel@freebsd.org> References: <CAPyFy2AYeN9XNg=b0=JMWDC9ctWarfiZ-5zQorOPhguDJgxYpg@mail.gmail.com> <D9AF1C8B-431C-4359-988F-FDEEF8FAD981@bsdimp.com> <CAPyFy2CZYV%2B-5pDQjCA4Btct1VZUyEQUuL2iU1z07Ff-n2Y9Hg@mail.gmail.com> <CANCZdfqP3=%2BBHM_%2B=ZrNouGrXW5WAwHC87F2teEi%2BE2j-AMm6g@mail.gmail.com> <1449177325.6214.14.camel@freebsd.org>
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On Thu, Dec 3, 2015 at 3:15 PM, Ian Lepore <ian@freebsd.org> wrote: > On Thu, 2015-12-03 at 12:53 -0700, Warner Losh wrote: >> On Thu, Dec 3, 2015 at 12:55 AM, Ed Maste <emaste@freebsd.org> wrote: >> >> > On 3 December 2015 at 05:51, Warner Losh <imp@bsdimp.com> wrote: >> > > >> > > I noted in the review that I don=E2=80=99t like the default being no= . >> > > >> > > I also don=E2=80=99t like that we=E2=80=99re growing lots of differe= nt knobs that need >> > > to be set to get a repeatable build. Let=E2=80=99s have one, or barr= ing that, >> > > let=E2=80=99s have one that sets all the sub-knobs. >> > >> > My hope is that we'll have a reproducible build by default, and that >> > *no* knobs need to be set. That's what I intend with my patch. I can >> > rename the knob to WITH_/WITHOUT_REPRODUCIBLE_BUILD though if that's >> > generally desired. If there's a consensus to default to including the >> > metadata I'm fine with setting it in make release. >> >> >> I think this an unwise decision in the current form suggested. The kerne= l >> metadata has saved my butt enough times I really don't want to see it >> go by default. But see below for a reasonable (imho) middle ground that >> would be a good default. >> > > I'm curious why anyone wants this enabled by default, like... are we > missing something? Does it improve freebsd-update behavior maybe? > > If it's just for some general "reproducibility is good" philosophy then > I would counter with "information is even better, so don't throw it > away without a good reason." > > Reproducibility is good for some people, and completely useless for > others, and the people who need it aren't going to mind turning on a > knob or two to get what they want. > >> >> > > I think that host and path are more worthless than date and time >> > > in many environments. Who builds it likewise. Those are all things >> > > that are likely to change between builds, yet change the kernel >> > > image. I=E2=80=99d rather see it all gone when this option is in eff= ect. >> > >> > I don't follow -- other than the build iteration number (which I >> > indeed missed), it is all gone. >> > >> >> Yea I was reading things backwards. >> >> In the review, I suggested that if you've modified the tree (which the S= CM >> will tell you), then do the old format to preserve useful metadata that'= s >> really really needed and if not to use the shorter version. When you've >> modified the tree, reproducible builds aren't a concern at all. >> > > How are you going to determine what consitutes a modified tree? What > you think of as modifications may be what I call my baseline version. > > -- Ian svnversion resulting in a 'nnnnnnM'? - Justin
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