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    SubjectRe: [PATCH] x86/kbuild: enable modversions for symbols exported from asm
    On Fri, 25 Nov 2016 10:00:46 -0800
    Linus Torvalds <torvalds@linux-foundation.org> wrote:

    > On Thu, Nov 24, 2016 at 4:40 PM, Nicholas Piggin <npiggin@gmail.com> wrote:
    > >>
    > >> Yes, manual "marking" is never going to be a viable solution.
    > >
    > > I guess it really depends on how exactly you want to use it. For distros
    > > that do stable ABI but rarely may have to break something for security
    > > reasons, it should work and give exact control.
    >
    > No. Because nobody else will care, so unless it's like a single symbol
    > or something, it will just be a maintenance nightmare.

    Yeah that's true, and as I realized a distro can rename a symbol if they
    make incompatible changes which happens very rarely. Avoids having to
    carry some whole infrastructure upstream for it.

    >
    > > What else do people *actually* use it for? Preventing mismatched modules
    > > when .git version is not attached and release version of the kernel has
    > > not been bumped. Is that it?
    >
    > It used to be very useful for avoiding loading stale modules and then
    > wasting days on debugging something that wasn't the case when you had
    > forgotten to do "make modules_install". Change some subtle internal
    > ABI issue (add/remove a parameter, whatever) and it would really help.
    >
    > These days, for me, LOCALVERSION_AUTO and module signing are what I
    > personally tend to use.
    >
    > The modversions stuff may just be too painful to bother with. Very few
    > people probably use it, and the ones that do likely don't have any
    > overriding reason why.
    >
    > So I'd personally be ok with just saying "let's disable it for now",
    > and see if anybody even notices and cares, and then has a good enough
    > explanation of why. It's entirely possible that most users are "I
    > enabled it ten years ago, I didn't even realize it was still in my
    > defconfig".

    That sounds good. Should we try to get 4.9 working (which we could
    do relatively easily with a few arch reverts), and then disable
    modversions for 4.10? (at which point we can un-revert Al's arch
    patches)

    Thanks,
    Nick

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