Date: Wed, 20 Nov 2019 12:02:03 -0800 From: bob prohaska <fbsd@www.zefox.net> To: Warner Losh <imp@bsdimp.com> Cc: FreeBSD Current <freebsd-current@freebsd.org>, bob prohaska <fbsd@www.zefox.net> Subject: Re: Reverting -current by date. Message-ID: <20191120200203.GA461@www.zefox.net> In-Reply-To: <CANCZdfr2o5SkCeDBxjvoiL_kjyp5VXdpLboDrcx5PicyHHscaQ@mail.gmail.com> References: <20191120173853.GB311@www.zefox.net> <CANCZdfr2o5SkCeDBxjvoiL_kjyp5VXdpLboDrcx5PicyHHscaQ@mail.gmail.com>
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On Wed, Nov 20, 2019 at 11:18:41AM -0700, Warner Losh wrote: > On Wed, Nov 20, 2019 at 10:39 AM bob prohaska <fbsd@www.zefox.net> wrote: > > > From time to time it would be handy to revert freebsd-current to > > an older, well-behaved revision. > > > > Is there a mechanism for identifying revision numbers that > > will at least compile and boot, by date? > > > > Almost all of them will compile. Almost all of those will boot. While some > build breakage sneaks through, the default assumption is that it's good. > That's certainly been my experience randomly updating to -current. There's > some that are more or less performant, mind you, and some that are more or > less stable, it is true. But the overwhelming vast majority will compile > and boot, at least for amd64. I have issues less than 1% of the time when > updating to whatever is current at the moment I fancy an update. > Are commits that depend on one another somehow grouped in a single revision? > There's some hardware that gets broken from time to time, but we don't > track that specifically. And non-amd64 architectures takes more care and > planning as any build breakage for those platforms lasts longer, in direct > proportion to how popular the platform is.... > Point taken. I'm interested in aarch64, which puts me somewhat in the weeds. > It's all in the commit logs. If you run -current you need to read them. > They will also tell you almost always if you pick revision X if there was a > subsequent fix that made things compile you should go with. > I take it the strategy would be go back in the log to a rough date, then browse forward in time looking for signs of major trouble. When the commits turn minor/benign, select a revision from that timeframe. > > Study the commit logs? I know I'm harping on that, but when things go > wrong, that's what I do. > I hoped for a more mechanical approach. For example, snapshots are generated from time to time. Presumably, they're vetted in some way and knowing what revisions made it to the snapshot stage might be a starting point. The snapshot server does not appear to contain that information for earlier offerings. > Also -DNO_CLEAN builds help a lot if you're worried about it not even > building, though from time to time you run into issues with a NO_CLEAN > build due to a recent commit that wasn't appreciated at the time of the > commit, but was later and fixed. > Does -DNO_CLEAN behave sanely (and usefully) when going backwards in time? I commonly use it for small forward steps, but time reversal is tricky 8-) Thanks for replying! bob prohaska
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