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List:       linux-kernel
Subject:    Re: [NEW PATCH] timers, sysctl, signal (only to get POSIX timers
From:       Riley Williams <rhw () MemAlpha ! CX>
Date:       1999-08-07 20:47:31
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Hi Albert.

 >>> Point taken, are you sure that all platforms can do 64 bit
 >>> calculations? (or does the compiler support it?)

 >> My understanding is that all platforms CAN do 64 bit calculation,
 >> but it's generally frowned upon on 32-bit platforms as it's rather
 >> slow.

 > First of all, one can not avoid wide numbers for this. You can
 > not use an #ifdef to avoid the problem.

 > The question then becomes: Use "long long" or not?

 > All platforms can do 64-bit calculations via "long long", with
 > the compiler emulating as needed. Older versions of gcc could be
 > slow, but this problem has been fixed.

It's not a gcc problem, but a general dislike of non-native integer
formats by the kernel developers. Personally, I've nothing against it
at all, but I've seen several patches rejected simply because they
used long long on 32-bit platforms.

 > Even though I have an old gcc, I'd prefer letting the compiler
 > handle the job. Using "long long" would make the code more
 > maintainable. Somebody actually using this new feature will need
 > a new libc anyway, and I think libc now requires the newer
 > compiler.

Remember that libc can't be used in the kernel itself...

Best wishes from Riley.

+----------------------------------------------------------------------+
| There is something frustrating about the quality and speed of Linux  |
| development, ie., the quality is too high and the speed is too high, |
| in other words, I can implement this XXXX feature, but I bet someone |
| else has already done so and is just about to release their patch.   |
+----------------------------------------------------------------------+
 * ftp://ftp.MemAlpha.cx/pub/rhw/Linux
 * http://www.MemAlpha.cx/kernel.versions.html


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