On Thu, Oct 24, 2013 at 10:57:11AM +0200, Richard Weinberger wrote: > On Thu, Oct 24, 2013 at 10:41 AM, Josh Triplett <josh@xxxxxxxxxxxxxxxx> wrote: > > Discussion at Kernel Summit made it clear that the presence or absence > > of specific Kconfig symbols are not considered ABI, and that no > > userspace (or bootloader, etc) should rely on them. > > > > In addition, kernel-internal symbols are well established as non-ABI, > > per Documentation/stable_api_nonsense.txt. > > > > Document both of these in Documentation/ABI/README, in a new section for > > notable bits of non-ABI. > > > > Signed-off-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx> > > --- > > Documentation/ABI/README | 13 +++++++++++++ > > 1 file changed, 13 insertions(+) > > > > diff --git a/Documentation/ABI/README b/Documentation/ABI/README > > index 1006982..1fafc4b 100644 > > --- a/Documentation/ABI/README > > +++ b/Documentation/ABI/README > > @@ -72,3 +72,16 @@ kernel tree without going through the obsolete state first. > > > > It's up to the developer to place their interfaces in the category they > > wish for it to start out in. > > + > > + > > +Notable bits of non-ABI, which should not under any circumstances be considered > > +stable: > > + > > +- Kconfig. Userspace should not rely on the presence or absence of any > > + particular Kconfig symbol, in /proc/config.gz, in the copy of .config > > + commonly installed to /boot, or in any invocation of the kernel build > > + process. > > + > > +- Kernel-internal symbols. Do not rely on the presence, absence, location, or > > + type of any kernel symbol, either in System.map files or the kernel binary > > + itself. See Documentation/stable_api_nonsense.txt. > > And what about the kernel make "interface", is it considered also as non-ABI? > > E.g. > Before ffee0de (x86: Default to ARCH=x86 to avoid overriding CONFIG_64BIT) > "make defconfig ARCH=x86" produced a i386 defconfig. Now it produces a > x86_64 defconfig. > I'm sure some build scripted failed badly. I seriously considered including that, but I could imagine that some parts of that interface might be considered more stable than others (the names of targets, for instance), and I wanted to stick to completely uncontroversial items. If there's consensus that part or all of the invocation of "make" to build the kernel is non-ABI, we can easily enough add that to the non-ABI list, but let's start with Kconfig and symbols. - Josh Triplett -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
