Re: [PATCH] Documentation/ABI: Document the non-ABI status of Kconfigand symbols

From: Richard Weinberger
Date: Thu Oct 24 2013 - 04:57:21 EST


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.


--
Thanks,
//richard
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