In message <[EMAIL PROTECTED]> you wrote: > > Huh? Normally the commit IDs are the most important thing I care about > when working with other git repositories. If I try to compare my > git repositroy with another one (mostly the u-boot master branch at > denx) then the commit ID is the only way (I know) to make sure that > my respository contains the exactly same patches than the other > repository. If the topmost patch (or any other) in my respository has
But this does not work. Assume you and me start with absolutely identical copies of the same git repository - say we copied a disk. Now we both check in the very same patch from the mailing list using for example git-am. You will see that we get two different commit IDs. Even if you try to do this twice to identical copies of the git repo you will get different IDs: -> rm -fr foo -> tar zxf foo.tgz ; cd foo ; echo x >xxx ; git-add xxx; git-commit -m test Created commit 8c934ae: test 1 files changed, 1 insertions(+), 1 deletions(-) -> cd .. -> rm -fr foo -> tar zxf foo.tgz ; cd foo ; echo x >xxx ; git-add xxx; git-commit -m test Created commit b5ae18e: test 1 files changed, 1 insertions(+), 1 deletions(-) -> cd .. -> rm -fr foo -> tar zxf foo.tgz ; cd foo ; echo x >xxx ; git-add xxx; git-commit -m test Created commit 56eb723: test 1 files changed, 1 insertions(+), 1 deletions(-) You see? Three identical commits, three different commit IDs. > As far as I understand the git philosophy, using SHA1 signatures as > commit IDs was one of the most important things on git. IMO the goal Yes, of course. And the SHA1's of the *objects* are of course the same. But the commit IDs may be different - they include for example the commiter's name and time etc., so they will be different even when you do the very same action again in the very same copy of a repository. See above. Note that git is tracking content, not history. > behind that was to be able to refere to one particular state in a > git repository by one single commit ID. If I have two git repositories > with de facto the same content, but with different commit IDs, what's > the worth of the SHA1 commit ID? You can still compare the commits. Just not the commit IDs. > I often use for example the (partial) commit ID in the U-Boot boot > message to identify from wich particular source state a U-Boot was This is OK, as long as you are referring to some repository for which you have a guarantee that the history will not be rewritten. > built. This only works, if the order of patches is the same in all > git repositories resulting in the same commit IDs. Otherwise I need No, this has nothing to do with that. > to know from wich git repository the U-Boot was built, to identify Yes, of course you need to know that. As soon as you are working n your own tree it may have commits that are present nowhere else. Only as long as you are referring to a known common history you can make references to another repo. > the source state it was built from. And then I can't compare this > repository to another (e. g. the denx master), because the same > patches could have different commit IDs. But they will result in the very same content (objcts in the git repo), and git is tracking the content, not the commit ID. > I tried this already some time ago (merging my u-boot-tq-group > master branch, instead of rebasing) and get totally lost in a > screwed up history. But maybe I did something wrong. Most probably (or this was with older versions of the tools - as mentioned before, I screwed up more than one repo before ;-) Best regards, Wolfgang Denk -- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: [EMAIL PROTECTED] e-credibility: the non-guaranteeable likelihood that the electronic data you're seeing is genuine rather than somebody's made-up crap. - Karl Lehenbauer ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ U-Boot-Users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/u-boot-users
