Date: Fri, 11 Jun 2010 07:56:10 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-hackers@freebsd.org Cc: Kostik Belousov <kostikbel@gmail.com>, Alexander Leidinger <Alexander@leidinger.net>, Adrian Chadd <adrian@freebsd.org>, Garrett Cooper <yaneurabeya@gmail.com>, Ilya Bakulin <webmaster@kibab.com> Subject: Re: GSoC: registration of optional kernel features via sysctl: a question to the community Message-ID: <201006110756.10287.jhb@freebsd.org> In-Reply-To: <AANLkTimTVmKz2b50GWTDktRTqJaKMsxOz4Uuo6wJP2Rj@mail.gmail.com> References: <20100609121453.095d92b4@kibab.com> <20100610160109.19585782fyr3buw4@webmail.leidinger.net> <AANLkTimTVmKz2b50GWTDktRTqJaKMsxOz4Uuo6wJP2Rj@mail.gmail.com>
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On Friday 11 June 2010 12:28:58 am Adrian Chadd wrote: > How about exposing a simple userspace API for doing this, rather than > doing it via sysctl? > > That way you could "simply" tie alternative overrides in as needed for > builds (eg, environment variables setting overrides; and/or pointing > to a configuration file with such) but not affect any runtime > detection the rest of the system is doing. man 3 feature_present I don't see much practical use for spoofing. If there really was a desire for such a thing, then perhaps you could implement it in libc keyed off environment variables. It would perhaps be useful to have a feature_present(1) for ports that uses the API instead of using the sysctls directly, but I really don't think there are any useful cases for spoofing. At Y! we used kern.features.pae in kmod.mk to automatically enable PAE in standalone kernel module builds if the running kernel was using PAE since PAE alters the kernel ABI. -- John Baldwin
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