Best way to generate a git tree containing only a subset of commits from another tree?

[Anton Altaparmakov <aia21@cam.ac.uk>]

As subject, what is at present the best way to generate a git tree 
containing only a subset of commits from another tree.

So I have /usr/src/my-big-tree and /usr/src/linux-2.6 and now I want to 
add some of the commits in my-big-tree to the tree linux-2.6 so I can push 
out to Linus.

Preferable I would like to do it so that later when Linus has pulled from 
my /usr/src/linux-2.6 tree, I do a "git pull" of Linus' tree from 
/usr/src/my-big-tree and it all works correctly and I don't end up with 
the same commits twice.

Is that possible at all?

If not what can I do to do it cleanly?  Does git help in any way or do I 
literally have to export all my commits from /usr/src/my-big-tree to diff 
style patches and then throw away the tree, clone Linus tree after he has 
pulled my /usr/src/linux-2.6 tree and commit all my generated diff patches 
again?  That would be rather horrible to have to do...

I am happy to be pointed to a FAQ or RTFM if you tell me where to look for 
it...

Thanks a lot in advance!

PS. Please keep me CC:-ed as I am not on the git mailing list any more.

Best regards,

	Anton
-- 
Anton Altaparmakov <aia21 at cam.ac.uk> (replace at with @)
Unix Support, Computing Service, University of Cambridge, CB2 3QH, UK
Linux NTFS maintainer / IRC: #ntfs on irc.freenode.net
WWW: http://linux-ntfs.sf.net/ & http://www-stu.christs.cam.ac.uk/~aia21/