[OE-core] Fetch time optimization (svn : gcc/eglibc - git : linux-yocto)

[Eric Bénard]

Hi,

I noticed in from scratch builds for qemuarm that the longest time is
taken in fetching sources, especially those fetched using git
(linux-yocto for example) & svn (gcc, eglibc & co).

To reduce the fetch time would that make sense to 
- fetch gcc/glibc & co from the archive of a stable version and then
  apply patches on top of it (maybe patches stored in an archive
  fetched from oe's website and applied in bulk or patches stored in OE)
- do the same thing for the linux-yocto kernel or add a --reference
  option to the git fetcher so that we can provide a local tree as a
  reference ?

Do you have other ideas (appart from using a local mirror) to optimize
the fetch time ?

Thanks,
Eric