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    SubjectRe: Regression in "kbuild: fix if_change and friends to consider argument order"
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    On 2016-06-07 03:38, Zanoni, Paulo R wrote:
    > Hi
    >
    > I recently noticed that alternating between "make" and "make targz-pkg"
    > rebuilds the whole Kernel. This was not happening before. As a Kernel
    > developer, my build/install/test environment heavily relies on the fact
    > that "make targz-pkg" only quickly generates the tarball if everything
    > is already built, so this change is heavily impacting my development
    > environment.
    >
    > I did some bisection and concluded that the first bad commit is:
    >
    > commit 9c8fa9bc08f60ac657751daba9fccf828a36cfed
    > Author: Masahiro Yamada
    > Date: Sat May 7 15:48:26 2016 +0900
    > kbuild: fix if_change and friends to consider argument order
    >
    > I also verified that if I just revert this commit on top of the
    > most recent tree it goes back to the usual behavior.
    >
    > I read the commit message and it seems that some unneeded rebuilds are
    > somewhat expected, but I can't understand why such a change in the
    > command line like the one I did triggers everything to be rebuilt.
    > IMHO, it really shouldn't. I also wonder that maybe the regression I'm
    > experiencing was not expected in the original change, so maybe there's
    > a way to keep the original improvement caused by the mentioned patch
    > without the regression I'm experiencing.
    >
    > How to reproduce (exact commands I used at every bisect step):
    >
    > $ make tinyconfig
    > $ time make -j4 V=2 # this should build things
    > $ time make -j4 V=2 # just to make sure nothing will be rebuilt
    > $ time make -j4 V=2 targz-pkg

    I can reproduce it.

    Michal

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