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Date: Mon, 8 Apr 2013 23:26:02 +0200
From: Szabolcs Nagy <nsz@...t70.net>
To: musl@...ts.openwall.com
Subject: Re: vfprintf.c:(.text+0xc6c): undefined reference to
`__signbitl'
* meres5@...ha.tmit.bme.hu <meres5@...ha.tmit.bme.hu> [2013-04-08 22:41:28 +0200]:
> >
> > gcc -dM -E - </dev/null |grep LDBL_
>
> meres5@...ha:~/src/eglibc/ports$ gcc -dM -E - </dev/null |grep LDBL_
> #define __LDBL_MAX__ 1.79769313486231580793728971405301e+308L
> #define __LDBL_MAX_EXP__ 1024
> #define __LDBL_HAS_INFINITY__ 1
> #define __LDBL_MIN__ 2.00416836000897277799610805135016e-292L
> #define __LDBL_HAS_QUIET_NAN__ 1
> #define __LDBL_HAS_DENORM__ 1
> #define __LDBL_EPSILON__ 4.94065645841246544176568792868221e-324L
> #define __LDBL_MANT_DIG__ 106
this is bad, it is 'double-double' long double format
which means broken long double arithmetics
> #define __LDBL_MIN_EXP__ (-968)
> #define __LDBL_MAX_10_EXP__ 308
> #define __LDBL_DENORM_MIN__ 4.94065645841246544176568792868221e-324L
> #define __LDBL_MIN_10_EXP__ (-291)
> #define __LDBL_DIG__ 31
>
> I won't like to descend so deep.
> I've just like to demo the difference between static and
> dynamic linking to our students, and came up here - LOL!
if you want to play with static linking then it's better
not to use soft-float long double, that ruins it a lot
(every trivial program will get an entire floating point
emulation library linked in from libgcc pulled in by printf
so the students will get the impression that static linking
always gives bloated binaries..)
the correct thing to do is to build a toolchain with 64bit
long double
> Anyway, it's been 19 years passed, so my guide seemed not so
> durable.
> Also Linux dropped the concept of static linking in practivce.
> Goodby kiss to
linux did not drop it, but for some reason the glibc and
binutils maintainers thought that dynamic linking is always
better so it's enough to support that
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