Date: Sat, 07 Aug 2010 21:18:47 +0200 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-hackers@freebsd.org Subject: Re: Why is TUNABLE_INT discouraged? Message-ID: <i3kbis$73l$1@dough.gmane.org> In-Reply-To: <86fwyq8rsc.fsf@ds4.des.no> References: <AANLkTinKaiGFhKRgqQ%2BFjm=02VfWCxULe0a68y-PkJx6@mail.gmail.com> <86fwyq8rsc.fsf@ds4.des.no>
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On 7.8.2010 15:40, Dag-Erling Smørgrav wrote: > Garrett Cooper <gcooper@FreeBSD.org> writes: >> I found the commit where it was made (by des@ -- cvs revision >> 1.120), but unfortunately I lack the context as to why that suggestion >> is made; the commit isn't very explicit as to why integers tunables >> should be discouraged > > You're supposed to use TUNABLE_LONG or TUNABLE_ULONG instead. From > digging in the -current archives, it seems that the motivation was a bug > that resulted from using a TUNABLE_INT for a value that was actually an > address. It was doubly broken: first because it was too small on 64-bit > systems, and second because it was signed. Ok, but still - if the underlying value really is declared as "int", doesn't it make perfect sense to have something like TUNABLE_INT for it? Forcing "long" is a bit weird in this context, as C long is 32-bit on i386 and 64-bit on amd64.
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