Re: [PATCH] make: add modules_update target

[Dustin Kirkland <dustin.kirkland@us.ibm.com>]

On Fri, 2006-04-14 at 22:02 +0300, Avi Kivity wrote:
> Use rsync only if it is available:
> 
>     rsync-available := $(shell rsync --version > /dev/null 2>&1 && echo y)
>     copy := $(if $(rsync-available), rsync --delete, cp)
> 
>     modules_install:
>                [...]
>                $(copy) source target

Actually, rsync --delete is not a viable option either.  If you first
build a kernel with a particular item built as a module, and then
afterward rebuild with the same item as built-in (or not at all),
the .ko file remains in your kernel build tree (ie, it won't be deleted
on the source such that the --delete would have your desired effect).

Furthermore, rsync's performance is considerably worse in my testing
than "cp -u", almost back to the original performance of the "rm -rf, cp
all" of the original modules_install.  (Note that I tested, rsync's
default, checksum, mod-times, and size-only.)

:-Dustin