Date: Mon, 23 Jun 2014 19:42:27 -0600 From: Warner Losh <imp@bsdimp.com> To: Glen Barber <gjb@FreeBSD.org> Cc: Craig Rodrigues <rodrigc@FreeBSD.org>, Brooks Davis <brooks@freebsd.org>, Dimitry Andric <dim@freebsd.org>, "Simon J. Gerraty" <sjg@juniper.net>, freebsd-current Current <freebsd-current@freebsd.org>, Marcel Moolenaar <marcel@freebsd.org> Subject: Re: Problems building FreeBSD 9.2 on FreeBSD 10 Message-ID: <60320DD3-56C4-4922-A537-FF94C392A45A@bsdimp.com> In-Reply-To: <20140624011251.GN1218@hub.FreeBSD.org> References: <CAG=rPVd4evnkJoz1rVeMjP7YNKOW0BWF0MvSrFQ3u2xCiVEtmw@mail.gmail.com> <690CE378-D7D9-49A6-BC20-13FD540E63A2@FreeBSD.org> <CAG=rPVfanU=FVWPd768_G5NjXRHnUH5o05%2BKwFeLaTQqU3Ux8w@mail.gmail.com> <FC1B2983-4B49-4480-855E-6BD09B148F31@bsdimp.com> <CAG=rPVd5XGz8hfuBtcOuuZp8ND1ssWoTkVNn0Hg6Li_2-NrgcA@mail.gmail.com> <1ED3AC7E-0F74-46A7-BAAA-E30600DC23BB@bsdimp.com> <CAG=rPVeP32=y3VZgn0MXFPrr8tevL=jOsCow=rvpxRevmvoLqA@mail.gmail.com> <8CD24B0A-DF45-4437-BEBE-8C67B241DE93@bsdimp.com> <CAG=rPVcrJpP_1VcKZnsxAugBywJBXg63p2piX7nPndTunPEWDQ@mail.gmail.com> <2063888D-CCAE-431B-A409-F17AA4422006@bsdimp.com> <20140624011251.GN1218@hub.FreeBSD.org>
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--Apple-Mail=_DD61DB34-0FD3-4459-9BDB-32F5E9522E2B Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=windows-1252 On Jun 23, 2014, at 7:12 PM, Glen Barber <gjb@FreeBSD.org> wrote: > On Mon, Jun 23, 2014 at 06:57:15PM -0600, Warner Losh wrote: >> On Jun 23, 2014, at 6:15 PM, Craig Rodrigues <rodrigc@FreeBSD.org> = wrote: >>> So, I guess that stable/9 can build properly on a stable/10 box. >>> For FreeBSD 9.2, there is no easy way out. >>=20 >> You=92ll have to back port the patch then. We don=92t guarantee = forward >> compatibility like this since 9.2 is frozen in time now. >>=20 >=20 > I'd really like to discuss rethinking our forward-compatibility > policies, since we have (now) 3 active stable/ branches, plus head/.=20= Generally, in the past, the rule has been =93head will build from the = last stable branch tip.=94 This was extended, for a while, to =93last = stable branch point=94 when Ruslan made sure that worked. While -stable = has generally built on -head, this was never part of the contract. It = usually did, but is very very hard to guarantee given the nature of = head=92s tools changing in ways that are allowed for head, but that = break prior branches. > What I would like to see, with my RE hat on, is a "best effort" > backwards compatibility to being able to build the lowest-numbered > supported stable/ branch on head/. I think, that as in the past, this will generally work. However, it = won=92t always work. Things break in this area a lot. More than you = might think, especially with the huge amount of churn we=92ve had wrt = compilers, make, etc. I suspect that new imports of clang will break = this every time, since every import of clang has required changes to the = tree to either disable warnings, or to fix newly flagged things. I = suspect there will be a lot of churn here, and releases will go stale = the fastest=85 With -current starting to support building multiple = versions of clang (and gcc), there=92s hope for the future, but = back-porting this code is beyond what I have the time to do. That=92s = going to make things increasingly difficult as we march forward. This isn=92t even getting into cross build scenarios=85. Or building releases, which is a whole different set of lightly tested = code that is mostly host independent, but sometimes isn=92t as much as = you=92d had hoped... > Sure, this won't always work, but "best effort" is better than "no > effort", which the latter is why we do not have stable/8 snapshot > builds, to be honest. I won't spend the time on the stable/8/release/ > code nor the snapshot build scripts to waste the time. Building > stable/9 on head/ is annoying alone. stable/9 builds on head. If there=92s a race, that needs to be fixed in = stable/9. That=92s quasi supported because people do it. The =93best = effort=94 involves people that are interested in the bugs being fixed = fixing them, or convincing others to fix them. For me, this scenario is = outside the area I care about, have the ability to test, or have time = for. So =93best effort=94 involves more than me making an effort. I may or I = may not. It all depends on my time and inclination. If it is going to = work, bugs need to be fixed in stable/9 that prevents it from building = on head, while not breaking the ability to build on 9. So there=92s a = lot of heavy lifting that will be needed in short order to keep this = working once the clang folks can figure out how to get past the angst of = the upgrade path and push forward to 3.5. Some architectures will break = when that happens, no doubt. But 9.2 will never build on head because it is broken with bmake, which = is now standard for head. Since 9.2 cannot be changed, and since we=92ve = removed (or nearly) fmake in current, chances are quite good it will = never build on head again without some special handling. In summary, good luck! there=92s a lot of use cases here, and it will = take time and effort of multiple people over the long haul to keep it = working. Best effort may be larger than you estimate=85 I won=92t stand = in your way, but I=92m afraid my time available to help is limited. Warner --Apple-Mail=_DD61DB34-0FD3-4459-9BDB-32F5E9522E2B Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP using GPGMail -----BEGIN PGP SIGNATURE----- Comment: GPGTools - https://gpgtools.org iQIcBAEBCgAGBQJTqNeDAAoJEGwc0Sh9sBEAW34P/j6piRRxQNGqYDyrCIb3eiKT py5v64urwDGP18QkFbzjXE1QfkqgbkPpRM40+xgWRRNsfgn/zmFUiFvTeBy66wB3 CnnRpcrppS2mSFv1V7xbDN8Dgtu7ibNRkK0zTrlHLqRmfoZp6pcSaFo9OripIP04 pCNfIp0vpDTj8PKYIBOeh/WuzFO2YGOA0XidjEjnxN1iWlhZbjjCeBvlV2drD3V1 qeiTALTLEWSOEuxl0LYernfTRSAR5d8KKd8LvDLvqFkRqWTgMY8Pn/ik+HdAg0wx dk/O13DUumgKmp62AtUSOIJ+XrEJ+xXQwfDNmAGw2Tsa6sd9LxlGY69am1z/r5k6 orhdh783koeP5aCT4iNGLxV2qPuAxpDySICh6hX58n4h5qfZfj5u32iWfPzqT9dB u644GCuKz/HOkdg9DGjPctKKiphobzoNprBgKot51LtNkh/OLBpWvpmE4DHh+88I laXeqzbwAn/HLaPDgrWj6an5aOaHXgW0IMLvwLmP85FyJ34VZt8w74tvpZltIQ+A bs5cYfcobJzs/oYwGpDEJzYlbJhub/IprBUcDNMTAN5iAoHrDZ84Pg7RKjrxWKoa jW5zR/w35DKRIy0dEaOsPGQ86JLy2zBXEkhE6ts+Ft2HUVid3KT0RXk3TskkC2pE LYl7lu2Vhyj6B487dvpg =s6Lq -----END PGP SIGNATURE----- --Apple-Mail=_DD61DB34-0FD3-4459-9BDB-32F5E9522E2B--
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