Bisecting using git

Linus Torvalds torvalds at linux-foundation.org
Fri Oct 20 03:31:21 PDT 2017


On Fri, Oct 20, 2017 at 6:07 AM, Willem Ferguson
<willemferguson at zoology.up.ac.za> wrote:
>
> willem at FINS:~/src/subsurface$ git bisect good 4.6.4-1003
> fatal: Needed a single revision
> Bad rev input: 4.6.4-1003
>
> I have no way of defining 4.6.4.1003 better.

Yeah, the subsurface package naming isn't really sufficient. It's
generated from git data: "1003 commits after the 4.6.4 release", but
that's not actually a unique identifier. There can be multiple ways to
do 1003 commits after a release in the same repository.

In this particular case, it happens to be unambiguous, since
subsurface development is *largely* linear, and Dirk makes releases
from the released tree.

So that commit is 1fe76b02d ("Connect finished signal of download
thread only once").

It would be better if the releases had the actual "git describe"
output, which contains the git hash in it:

   git describe 1fe76b02d

results in

    v4.6.4-1003-g1fe76b02d

but it's obviously also longer and a somewhat ugly name.

That said, I suspect it's not necessarily a code base issue, as much
as a configuration or build issue, in which case "git bisect" will
*not* work at all for you, since the problem is then not the revision
but the way it got built.

              Linus


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