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Old 07-19-2015, 07:00 PM   #1
Registered: Apr 2014
Distribution: debian
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Floatin point or fixed point in packaged binaries?

If I use
apache/nginx, cgi/php, etc..
samba, postfix/exim/sendmail...

on debian linux

I use floating point or fixed point in these softwares?

I mean in the above "standard" programs ( not in the php scripts or in any other user programs ).

Debian's packages are still 386 compatibles. Is this decided by the gcc (or other compiler) when the package maintainer compiles the program?
Is it an architectural question? Will the program works differently for example on a sparc and on an 64bit xeon? Or the program's source determines the usage of the FPU?

Is there a debugger/audit subsystem/source analyser to get the fpu usage of a program?
Old 07-20-2015, 01:31 AM   #2
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You can also analyze the source code of these programs. (filetype float). Just download these packages from the appropriate pages ( , , ...)

And the FPU does not always use floating point.

Try to install Gentoo and activate FPU.

Last edited by Keruskerfuerst; 07-20-2015 at 07:24 AM.
Old 07-20-2015, 07:34 AM   #3
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All implementations of the 386 architecture today include a built-in FPU which is used for all floating-point operations. The CPU also has a decimal mode. If it is a 32-bit program, the CPU will operate in 32-bit compatibility mode if it is a 64-bit unit.

Last edited by sundialsvcs; 07-20-2015 at 07:35 AM.
Old 07-20-2015, 08:54 AM   #4
Registered: Apr 2014
Distribution: debian
Posts: 42

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yes, "386 architecture" or x86 has builtin fpu nowadays, but what about sparc T1 many cores, but only one fpu, or my dns 313 nas ( Processor : FA526id(wb) rev 1 (v4l) ).
Gcc has some fpu emulation like thing as I can see, and the kernel itself has math emulation.
And as I remember, the "i387" external coprocessor was the hardware fpu unit, not the "386", so if debian ships "386 compatible" binaries it should mean in this context that there are floating point instructions in the code, and it relies on the kernel with fpu emulation?

If the system doesn't have an fpu that is clear. I think the interesting part is for example the T1, 8 cores, 32 threads, but only one fpu. Maybe a threaded emulation in the kernel, or a "workaround" by gcc - as for no fpu arm platforms performs better?

Anyway I will check the sources of the packages ( not the original ones, since debian is not always using the vanilla softwares, and now I focuses on that distribution ).


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