GSoC: registration of optional kernel features via sysctl: a question to the community

[Kostik Belousov]

On Wed, Jun 09, 2010 at 09:13:56AM -0400, jhell wrote:
> On 06/09/2010 04:14, Ilya Bakulin wrote:
> > Hi hackers!
> > 
> > While discussing my project's implementation details with my mentor,
> > Alexander Leidinger, we've found that one of the ideas needs to be discussed with community,
> > to find out possible use cases.
> > That is, if it should be possible to spoof non-existing features. For
> > example, if currently running kernel doesn't support FreeBSD 5.0 compat
> > layer, "kern.features.compat_freebsd5" will be absent when querying 
> > features list. The question is -- are there any cases when we want
> > "kern.features.compat_freebsd5" be present? If some feature is not in
> > kernel, then presenting its existence to the userland is useless
> > and may be even harmful, if, for example, some application relies on this feature.
> > Or there are some scenarios where such cheat is useful?
> > 
> 
> I can not think of any viable reason why one would want to "spoof" this
> when it is not available.
Many ports are doing wrong thing there, checking for run-time features at
the build-time, turning on/off some functionality depending on its
presence on the build host.
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