Re: [Qemu-devel] Switch to GIT. Why?

[Lennart Sorensen]

On Mon, Apr 27, 2009 at 07:54:32AM -0600, M. Warner Losh wrote:
> Yes.  And that's why you can only check out entire trees, and never
> subtrees, with git and hg, but you can with svn.  git and hg force a
> small view of the system to be its own repo.  So something the size of
> X11 or FreeBSD could never use git or hg without breaking the
> integrated tree model.  FreeBSD used svn to not break it because we
> like the development model we have (and think Linus' talk at google
> was very arrogant to suggest it was broken), while the X11 folks broke
> their tree up into lots of modules, and got out of the making sure it
> all worked together business (which makes integrating X11 into systems
> harder now, alas).

It is certainly a tradeoff.  Of course with svn, when you do a checkout,
you get one version of the code.  If you want to search te history,
you have to talk to the server.  With git a "checkout" (clone) gets you
everything, history and all.  Makes searches and switching revisions
much faster, but makes the initial copy take much longer.

What X11 did also made it much easier to fix bugs, since you can now
work on the smaller pieces and release them much easier than you can
release the whole thing.  As for making sure it all works together,
I am not convinced it made it harder.  Seems development and such has
gotten much faster and better as a result.  It is no longer completely
overwhelming to work with.

> For qemu, none of these issues are likely to be an issue, but it is
> something to keep in mind...

True.  Of course as long as you have one tree per application, even
freebsd should be able to work with something like git.  Having one
giant tree for everything sounds nuts to me.  No idea how they do it
(I can't stand the userland of BSD in general, so I don't work with it.
Good applications, good kernel, lousy setup. :)  Debian kfreebsd may
change that of course.)

-- 
Len Sorensen