svn commit: r253662 - in head: lib/libc/gen sys/vm tools/tools/sysdoc

[Bruce Evans]

On Fri, 26 Jul 2013, Juli Mallett wrote:

> On Fri, Jul 26, 2013 at 2:26 PM, Andrey Zonov <zont at freebsd.org> wrote:
>
>> On 7/26/13 8:09 AM, Jilles Tjoelker wrote:
>>> As noted in mail from Bruce Evans, please preserve the ABI of
>>> VM_SWAPPING_ENABLED here.
>>
>> I don't think it's a big problem.  Internally we don't use it.  Good
>> code uses sysctlbyname() instead of sysctl().  It doesn't seem to me
>> this is very popular sysctl.  It's also CURRENT without MFC.
>
> That doesn't seem like a great argument.
>
> Why should we break the ABI for bad code that used that sysctl and all
> following?  It seems pretty trivial to preserve, and no-cost.  Also, the
> fact that it's in current misses the point completely: it breaks ABI with
> older binaries, namely older binaries running on -CURRENT.  And not just
> for that field.

Especially since the main reason numbered sysctls exist is to support old
binaries (and sources) that use them.

Bruce