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    SubjectRe: mmotm 2014-07-02-15-07 uploaded (stack protector)
    > The problem is that if you make kbuild hard-fail when selecting this missing
    > compiler option, you can never switch it back because "make menuconfig" will
    > refuse to build since the compiler option would be missing. Being silent
    > about the missing option (and/or falling back to other options) means that
    > you could get two different kernel features selection with the same CONFIG_*
    > set, depending on the kernel, which is extremely bad ("I selected
    > stack-protector-strong but it built without it?!").

    The assumption that every flag in a .config has been consciouscly
    selected by a human is a quite dubious one ...

    LTO just turns itself off if the toolchain doesn't support it.

    > So, the middle ground was to warn about it during the kbuild logic so
    > you could find the source of the problem, but ultimately fail the build
    > when the compiler doesn't support it so there weren't any silent failure
    > modes.

    Longer term it would be of course best to move all the cc-options
    probing into Kconfig. I bet that would speed up builds too.

    -Andi


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