From: Geert Uytterhoeven Date: Sun, 10 Aug 2014 21:08:31 GMT Subject: Re: [PATCH] checkpatch: Add test for commit id formatting style in commit log Message-ID: In-Reply-To: <1404338448.14741.8.camel@joe-AO725> Hi Joe, On Thu, Jul 3, 2014 at 12:00 AM, Joe Perches wrote: > Commit logs have various forms of commit id references. > > Try to standardize on a 12 character long lower case > commit id along with a description of parentheses and > the quoted subject line > > ie: commit 0123456789ab ("commit description") Now this is in mainline, checkpatch starts complaining about my "too long" (40 chars) commit IDs in commit messages :-( 40 chars may be too long (but it's quick to copy-and-paste, as "git show" shows that by default), but 12 sounds a bit short, as that's only 48 bits. According to the Birthday Paradox (en.wikipedia.org/wiki/Birthday_problem), there's a probability of 50% of a collision if you use 48 bits IDs in a repository with ca. 16 milion (2^24) objects. A Linux kernel repository counts ca. 4 million objects, so we're getting close... So soon we'll get "error: short SHA1 is ambiguous". BTW, is there actually an easy way to make "git show" show all options for an ambiguous SHA1? Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds