How old is our kernel?

“April 2005 was a bit of a tense time in the kernel development
community. The BitKeeper tool which had done so much to improve the
development process had suddenly become unavailable, and it wasn’t
clear what would replace it. Then Linus appeared with a new system
called git; the current epoch of kernel development can arguably be
dated from then. The opening event of that epoch was commit
1da177e4, the changelog of which reads:

“Initial git repository build. I’m not bothering with the full
history, even though we have it. We can create a separate
“historical” git archive of that later if we want to, and in the
meantime it’s about 3.2GB when imported into git – space that would
just make the early git days unnecessarily complicated, when we
don’t have a lot of good infrastructure for it.

“Let it rip!

“The community did, indeed, let it rip; some 180,000 changesets
have been added to the repository since then. Typically hundreds of
thousands of lines of code are changed with each three-month
development cycle. A while back, your editor began to wonder how
much of the kernel had actually been changed, and how much of our
2.6.33-to-be kernel dates back to 2.6.12-rc2, which was tagged at
the opening of the git era? Was there anything left of the kernel
we were building in early 2005?”

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