On Monday 05 May 2008 06:25:46 Bryan Donlan asked:
> On Wed, Apr 16, 2008 at 08:37:39AM +0200, Brian Foster wrote:
> > I've recently inherited a bare git repository,
> > which, as far as I can tell (I'm something of
> > a newbie with git), seems Ok: `git fsck --full'
> > does not report any problems. however, any
> > clones I make from it are not Ok [ ... ]
>
> Is there an info/grafts file? If the repository doesn't have sensitive
> information in it, it would probably be helpful to tarball it up and
> upload it somewhere, so we can take a look at things directly.
Bryan,
Yes, the proximate cause was an info/grafts.
The repository in question is for a port of Linux
to the MIPS-based "secure" SoC made by the company
I work for. The repository was very simple:
master: o---o---o---o---o--...--o HEAD
where each `o' was a tagged version/release of the
Linux port. Since the chip is MIPS-based, some `o'
were the result of merges with mips-linux baseline.
Hence, the real history was, broadly:
master: o--o--o--o--o--o-----o--...--o
/ / / /
mips-linux: o--o--o----o------o--o--o--o--...--o
where, of course, `mips-linux' has its own rather
complicated history (not shown). As implied by
the diagrams above, grafts were used to "suppress"
mips-linux and its history. (Since the situation
really was as trivial as drawn above, it was easy
to recover: Add the pack representing mips-linux,
remove grafts, and ensure all the tags exist.)
What I don't know is the root-cause, that is, WHY
this was done. It wasn't a disc-space issue, and
I've no evidence it was a network-bandwidth issue,
but there is some anecdotal evidence it was some
sort of a CPU-cycles issue, albeit just what the
performance hit was is unknown.
Another possibility is the repository started life
as CVS (ugh!) before being migrated to git. It's
my (vague) understanding grafts is somehow useful
as a (temporary?) aid when doing a CVS-->git move;
and I speculate it was found so useful/simple the
practice simply continued.
The developers tended to work from tarballs (not
clones), so the cloning problem was either unknown,
not a concern, or mis-understood.
cheers!
-blf-
--
"How many surrealists does it take to | Brian Foster
change a lightbulb? Three. One calms | somewhere in south of France
the warthog, and two fill the bathtub | Stop E$$o (ExxonMobil)!
with brightly-coloured machine tools." | http://www.stopesso.com
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