1 Frequently Asked Question on GNU C Library
3 As every FAQ this one also tries to answer questions the user might have
4 when using the package. Please make sure you read this before sending
5 questions or bug reports to the maintainers.
7 The GNU C Library is very complex. The building process exploits the
8 features available in tools generally available. But many things can
9 only be done using GNU tools. Also the code is sometimes hard to
10 understand because it has to be portable but on the other hand must be
11 fast. But you need not understand the details to use GNU C Library.
12 This will only be necessary if you intend to contribute or change it.
14 If you have any questions you think should be answered in this document,
19 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
20 [Q1] ``What systems does the GNU C Library run on?''
22 [Q2] ``What compiler do I need to build GNU libc?''
24 [Q3] ``When starting make I get only error messages.
27 [Q4] ``After I changed configure.in I get `Autoconf version X.Y.
28 or higher is required for this script'. What can I do?''
30 [Q5] ``Do I need a special linker or archiver?''
32 [Q6] ``Do I need some more things to compile GNU C Library?''
34 [Q7] ``When I run `nm -u libc.so' on the produced library I still
35 find unresolved symbols? Can this be ok?''
37 [Q8] ``Can I replace the libc on my Linux system with GNU libc?''
39 [Q9] ``I expect GNU libc to be 100% source code compatible with
40 the old Linux based GNU libc. Why isn't it like this?''
42 [Q10] ``Why does getlogin() always return NULL on my Linux box?''
44 [Q11] ``Where are the DST_* constants found in <sys/time.h> on many
47 [Q12] ``The `gencat' utility cannot process the input which are
48 successfully used on my Linux libc based system. Why?''
50 [Q13] ``How do I configure GNU libc so that the essential libraries
51 like libc.so go into /lib and the other into /usr/lib?''
53 [Q14] ``When linking with the new libc I get unresolved symbols
54 `crypt' and `setkey'. Why aren't these functions in the
57 [Q15] ``What are these `add-ons'?''
59 [Q16] ``When I use GNU libc on my Linux system by linking against
60 to libc.so which comes with glibc all I get is a core dump.''
62 [Q17] ``Looking through the shared libc file I haven't found the
63 functions `stat', `lstat', `fstat', and `mknod' and while
64 linking on my Linux system I get error messages. How is
65 this supposed to work?''
67 [Q18] ``The prototypes for `connect', `accept', `getsockopt',
68 `setsockopt', `getsockname', `getpeername', `send',
69 `sendto', and `recvfrom' are different in GNU libc than
70 on any other system I saw. This is a bug, isn't it?''
72 [Q19] ``My XXX kernel emulates a floating-point coprocessor for me.
73 Should I enable --with-fp?''
75 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
76 [Q1] ``What systems does the GNU C Library run on?''
78 [A1] {UD} This is difficult to answer. The file `README' lists the
79 architectures GNU libc is known to run *at some time*. This does not
80 mean that it still can be compiled and run on them in the moment.
82 The systems glibc is known to work on in the moment and most probably
86 i[3456]86-*-linux-gnu Linux-2.0 on Intel
87 m68k-*-linux-gnu Linux-2.0 on Motorola 680x0
88 alpha-*-linux-gnu Linux-2.0 on DEC Alpha
90 Other Linux platforms are also on the way to be supported but I need
91 some success reports first.
93 If you have a system not listed above (or in the `README' file) and
94 you are really interested in porting it, contact
96 <bug-glibc@prep.ai.mit.edu>
99 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
100 [Q2] ``What compiler do I need to build GNU libc?''
102 [A2] {UD} It is (almost) impossible to compile GNU C Library using a
103 different compiler than GNU CC. A lot of extensions of GNU CC are
104 used to increase the portability and speed.
106 But this does not mean you have to use GNU CC for using the GNU C
107 Library. In fact you should be able to use the native C compiler
108 because the success only depends on the binutils: the linker and
111 The GNU CC is found like all other GNU packages on
112 ftp://prep.ai.mit.edu/pub/gnu
113 or better one of the many mirror sites.
115 You always should try to use the latest official release. Older
116 versions might not have all the features GNU libc could use.
119 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
120 [Q3] ``When starting `make' I get only errors messages.
123 [A3] {UD} You definitely need GNU make to translate GNU libc. No
124 other make program has the needed functionality.
126 Versions before 3.74 have bugs which prevent correct execution so you
127 should upgrade to the latest version before starting the compilation.
130 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
131 [Q4] ``After I changed configure.in I get `Autoconf version X.Y.
132 or higher is required for this script'. What can I do?''
134 [A4] {UD} You have to get the specified autoconf version (or a later)
135 from your favourite mirror of prep.ai.mit.edu.
138 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
139 [Q5] ``Do I need a special linker or archiver?''
141 [A5] {UD} If your native versions are not too buggy you can probably
142 work with them. But GNU libc works best with GNU binutils.
144 On systems where the native linker does not support weak symbols you
145 will not get a really ISO C compliant C library. Generally speaking
146 you should use the GNU binutils if they provide at least the same
147 functionality as your system's tools.
149 Always get the newest release of GNU binutils available.
150 Older releases are known to have bugs that affect building the GNU C
154 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
155 [Q6] ``Do I need some more things to compile GNU C Library?''
157 [A6] {UD} Yes, there are some more :-).
159 * GNU gettext; the GNU libc is internationalized and partly localized.
160 For bringing the messages for the different languages in the needed
161 form the tools from the GNU gettext package are necessary. See
162 ftp://prep.ai.mit.edu/pub/gnu or better any mirror site.
164 * lots of diskspace (for i?86-linux this means, e.g., ~70MB).
166 You should avoid compiling on a NFS mounted device. This is very
169 * plenty of time (approx 1h for i?86-linux on i586@133 or 2.5h on
170 i486@66 or 4.5h on i486@33). For Hurd systems times are much higher.
172 If you have some more measurements let me know.
174 * When compiling for Linux:
176 + the header files of the Linux kernel must be available in the
177 search path of the CPP as <linux/*.h> and <asm/*.h>.
179 * Some files depend on special tools. E.g., files ending in .gperf
180 need a `gperf' program. The GNU version (part of libg++) is known
181 to work while some vendor versions do not.
183 You should not need these tools unless you change the source files.
185 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
186 [Q7] ``When I run `nm -u libc.so' on the produced library I still
187 find unresolved symbols? Can this be ok?''
189 [A7] {UD} Yes, this is ok. There can be several kinds of unresolved
192 * magic symbols automatically generated by the linker. Names are
193 often like __start_* and __stop_*
195 * symbols starting with _dl_* come from the dynamic linker
197 * symbols resolved by using libgcc.a
198 (__udivdi3, __umoddi3, or similar)
200 * weak symbols, which need not be resolved at all
201 (currently fabs among others; this gets resolved if the program
202 is linked against libm, too.)
204 Generally, you should make sure you find a real program which produces
205 errors while linking before deciding there is a problem.
208 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
209 [Q8] ``Can I replace the libc on my Linux system with GNU libc?''
211 [A8] {UD} You cannot replace any existing libc for Linux with GNU
212 libc. There are different versions of C libraries and you can run
213 libcs with different major version independently.
215 For Linux there are today two libc versions:
216 libc-4 old a.out libc
217 libc-5 current ELF libc
219 GNU libc will have the major number 6 and therefore you can have this
220 additionally installed. For more information consult documentation for
221 shared library handling. The Makefiles of GNU libc will automatically
222 generate the needed symbolic links which the linker will use.
225 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
226 [Q9] ``I expect GNU libc to be 100% source code compatible with
227 the old Linux based GNU libc. Why isn't it like this?''
229 [A9] {DMT,UD} Not every extension in Linux libc's history was well
230 thought-out. In fact it had a lot of problems with standards compliance
231 and with cleanliness. With the introduction of a new version number these
232 errors now can be corrected. Here is a list of the known source code
235 * _GNU_SOURCE: glibc does not automatically define _GNU_SOURCE. Thus,
236 if a program depends on GNU extensions or some other non-standard
237 functionality, it is necessary to compile it with C compiler option
238 -D_GNU_SOURCE, or better, to put `#define _GNU_SOURCE' at the beginning
239 of your source files, before any C library header files are included.
240 This difference normally manifests itself in the form of missing
241 prototypes and/or data type definitions. Thus, if you get such errors,
242 the first thing you should do is try defining _GNU_SOURCE and see if
243 that makes the problem go away.
245 For more information consult the file `NOTES' part of the GNU C
248 * reboot(): GNU libc sanitizes the interface of reboot() to be more
249 compatible with the interface used on other OSes. In particular,
250 reboot() as implemented in glibc takes just one argument. This argument
251 corresponds to the third argument of the Linux reboot system call.
252 That is, a call of the form reboot(a, b, c) needs to be changed into
254 Beside this the header <sys/reboot.h> defines the needed constants
255 for the argument. These RB_* constants should be used instead of the
256 cryptic magic numbers.
258 * swapon(): the interface of this function didn't changed, but the
259 prototype is in a separate header file <sys/swap.h>. For the additional
260 argument of of swapon() you should use the SWAP_* constants from
261 <linux/swap.h>, which get defined when <sys/swap.h> is included.
263 * errno: If a program uses variable "errno", then it _must_ include header
264 file <errno.h>. The old libc often (erroneously) declared this variable
265 implicitly as a side-effect of including other libc header files. glibc
266 is careful to avoid such namespace pollution, which, in turn, means that
267 you really need to include the header files that you depend on. This
268 difference normally manifests itself in the form of the compiler
269 complaining about the references of the undeclared symbol "errno".
271 * Linux-specific syscalls: All Linux system calls now have appropriate
272 library wrappers and corresponding declarations in various header files.
273 This is because the syscall() macro that was traditionally used to
274 work around missing syscall wrappers are inherently non-portable and
275 error-prone. The following tables lists all the new syscall stubs,
276 the header-file declaring their interface and the system call name.
278 syscall name: wrapper name: declaring header file:
279 ------------- ------------- ----------------------
280 bdflush bdflush <sys/kdaemon.h>
281 create_module create_module <sys/module.h>
282 delete_module delete_module <sys/module.h>
283 get_kernel_syms get_kernel_syms <sys/module.h>
284 init_module init_module <sys/module.h>
285 syslog ksyslog_ctl <sys/klog.h>
287 * lpd: Older versions of lpd depend on a routine called _validuser().
288 The library does not provide this function, but instead provides
289 __ivaliduser() which has a slightly different interfaces. Simply
290 upgrading to a newer lpd should fix this problem (e.g., the 4.4BSD
291 lpd is known to be working).
293 * resolver functions/BIND: like on many other systems the functions of
294 the resolver library are not included in the libc itself. There is
295 a separate library libresolv. If you find some symbols starting with
296 `res_*' undefined simply add -lresolv to your call of the linker.
299 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
300 [Q10] ``Why does getlogin() always return NULL on my Linux box?''
302 [A10] {UD} The GNU C library has a format for the UTMP and WTMP file
303 which differs from what your system currently has. It was extended to
304 fulfill the needs of the next years when IPv6 is introduced. So the
305 record size is different, fields might have a different position and
306 so reading the files written by functions from the one library cannot
307 be read by functions from the other library. Sorry, but this is what
308 a major release is for. It's better to have a cut now than having no
309 means to support the new techniques later.
312 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
313 [Q11] ``Where are the DST_* constants found in <sys/time.h> on many
316 [A11] {UD} These constants come from the old BSD days and are not used
317 today anymore (even the Linux based glibc does not implement the handling
318 although the constants are defined).
320 Instead GNU libc contains the zone database handling and compatibility
321 code for POSIX TZ environment variable handling.
324 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
325 [Q12] ``The `gencat' utility cannot process the input which are
326 successfully used on my Linux libc based system. Why?''
328 [A12] {UD} Unlike the author of the `gencat' program which is distributed
329 with Linux libc I have read the underlying standards before writing the
330 code. It is completely compatible with the specification given in
331 X/Open Portability Guide.
333 To ease the transition from the Linux version some of the non-standard
334 features are also present in the `gencat' program of GNU libc. This
335 mainly includes the use of symbols for the message number and the automatic
336 generation of header files which contain the needed #defines to map the
339 Here is a simple SED script to convert at least some Linux specific
340 catalog files to the XPG4 form:
342 -----------------------------------------------------------------------
343 # Change catalog source in Linux specific format to standard XPG format.
344 # Ulrich Drepper <drepper@cygnus.com>, 1996.
348 s/\$ #\([^ ]*\).*/\1/
350 s/\$ #[^ ]* *\(.*\)/\$ \1/
356 s/\(.*\)\n\(.*\)/\2 \1/
358 -----------------------------------------------------------------------
361 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
362 [Q13] ``How do I configure GNU libc so that the essential libraries
363 like libc.so go into /lib and the other into /usr/lib?''
365 [A13] {UD} Like all other GNU packages GNU libc is configured to use a
366 base directory and install all files relative to this. If you intend
367 to really use GNU libc on your system this base directory is /usr. I.e.,
369 configure --prefix=/usr <other_options>
371 Some systems like Linux have a filesystem standard which makes a
372 difference between essential libraries and others. Essential
373 libraries are placed in /lib because this directory is required to be
374 located on the same disk partition as /. The /usr subtree might be
375 found on another partition/disk.
377 To install the essential libraries which come with GNU libc in /lib
378 one must explicitly tell this. Autoconf has no option for this so you
379 have to use the file where all user supplied additional information
380 should go in: `configparms' (see the `INSTALL' file). For Linux the
381 `configparms' file should contain:
386 The first line specifies the directory for the essential libraries,
387 the second line the directory for file which are by tradition placed
388 in a directory named /etc.
391 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
392 [Q14] ``When linking with the new libc I get unresolved symbols
393 `crypt' and `setkey'. Why aren't these functions in the
396 [A14] {UD} Remember the US restrictions of exporting cryptographic
397 programs and source code. Until this law gets abolished we cannot
398 ship the cryptographic function together with the libc.
400 But of course we provide the code and there is an very easy way to use
401 this code. First get the extra package. People in the US way get it
402 from the same place they got the GNU libc from. People outside the US
403 should get the code from ftp.uni-c.dk [129.142.6.74], or another
404 archive site outside the USA. The README explains how to install the
407 If you already have the crypt code on your system the reason for the
408 failure is probably that you failed to link with -lcrypt. The crypto
409 functions are in a separate library to make it possible to export GNU
410 libc binaries from the US.
413 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
414 [Q15] ``What are these `add-ons'?''
416 [A15] {UD} To avoid complications with export rules or external source
417 code some optional parts of the libc are distributed as separate
418 packages (e.g., the crypt package, see Q14).
420 To ease the use as part of GNU libc the installer just has to unpack
421 the package and tell the configuration script about these additional
422 subdirectories using the --enable-add-ons option. When you add the
423 crypt add-on you just have to use
425 configure --enable-add-ons=des-crypt,XXX ...
427 where XXX are possible other add-ons and ... means the rest of the
430 You can use add-ons also to overwrite some files in glibc. The add-on
431 system dependent subdirs are search first. It is also possible to add
432 banner files (use a file named `Banner') or create shared libraries.
434 Using add-ons has the big advantage that the makefiles of the GNU libc
435 can be used. Only some few stub rules must be written to get
436 everything running. Even handling of architecture dependent
437 compilation is provided. The GNU libc's sysdeps/ directory shows how
441 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
442 [Q16] ``When I use GNU libc on my Linux system by linking against
443 to libc.so which comes with glibc all I get is a core dump.''
445 [A16] {UD} It is not enough to simply link against the GNU libc
446 library itself. The GNU C library comes with its own dynamic linker
447 which really conforms to the ELF API standard. This dynamic linker
450 Normally this is done by the compiler. The gcc will use
452 -dynamic-linker /lib/ld-linux.so.1
454 unless the user specifies her/himself a -dynamic-linker argument. But
455 this is not the correct name for the GNU dynamic linker. The correct
456 name is /lib/ld.so.1 which is the name specified in the SVr4 ABi.
458 To change your environment to use GNU libc for compiling you need to
459 change the `specs' file of your gcc. This file is normally found at
461 /usr/lib/gcc-lib/<arch>/<version>/specs
463 In this file you have to change a few things:
465 - change `ld-linux.so.1' to `ld.so.1' (or to ld-linux.so.2, see below)
467 - remove all expression `%{...:-lgmon}'; there is no libgmon in glibc
470 Things are getting a bit more complicated if you have GNU libc
471 installed in some other place than /usr, i.e., if you do not want to
472 use it instead of the old libc. In this case the needed startup files
473 and libraries are not found in the regular places. So the specs file
474 must tell the compiler and linker exactly what to use. Here is for
475 example the gcc-2.7.2 specs file when GNU libc is installed at
478 -----------------------------------------------------------------------
480 %{V} %{v:%{!V:-V}} %{Qy:} %{!Qn:-Qy} %{n} %{T} %{Ym,*} %{Yd,*} %{Wa,*:%*}
486 %{fPIC:-D__PIC__ -D__pic__} %{fpic:-D__PIC__ -D__pic__} %{!m386:-D__i486__} %{posix:-D_POSIX_SOURCE} -I/home/gnu/include
495 %{!shared:crtend.o%s} %{shared:crtendS.o%s} /home/gnu/lib/crtn.o%s
498 -m elf_i386 -rpath=/home/gnu/lib -L/home/gnu/lib %{shared:-shared} %{!shared: %{!ibcs: %{!static: %{rdynamic:-export-dynamic} %{!dynamic-linker:-dynamic-linker=/home/gnu/lib/ld.so.1}} %{static:-static}}}
501 %{!shared: %{mieee-fp:-lieee} %{p:-lc_p} %{!p:%{pg:-lc_p} %{!pg:-lc}}}
507 %{!shared: %{pg:/home/gnu/lib/gcrt1.o%s} %{!pg:%{p:/home/gnu/lib/gcrt1.o} %{!p:/home/gnu/lib/crt1.o%s}}} /home/gnu/lib/crti.o%s %{!shared:crtbegin.o%s} %{shared:crtbeginS.o%s}
509 *switches_need_spaces:
513 %{funsigned-char:-D__CHAR_UNSIGNED__}
516 -D__ELF__ -Dunix -Di386 -Dlinux -Asystem(unix) -Asystem(posix) -Acpu(i386) -Amachine(i386)
524 -----------------------------------------------------------------------
526 The above is currently correct for all systems but ix86/Linux.
527 Because of compatibility issues on this platform the dynamic linker
528 must have a different name: ld-linux.so.2. So you have to replace
530 %{!dynamic-linker:-dynamic-linker=/home/gnu/lib/ld.so.1}
532 %{!dynamic-linker:-dynamic-linker=/home/gnu/lib/ld-linux.so.2}
534 in the above example specs file.
536 Future versions of GCC will automatically provide the correct specs.
539 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
540 [Q17] ``Looking through the shared libc file I haven't found the
541 functions `stat', `lstat', `fstat', and `mknod' and while
542 linking on my Linux system I get error messages. How is
543 this supposed to work?''
545 [A17] {RM} Believe it or not, stat and lstat (and fstat, and mknod)
546 are supposed to be undefined references in libc.so.6! Your problem is
547 probably a missing or incorrect /usr/lib/libc.so file; note that this
548 is a small text file now, not a symlink to libc.so.6. It should look
551 GROUP ( libc.so.6 ld.so.1 libc.a )
554 {UD} The Linux ldconfig file probably generates a link libc.so ->
555 libc.so.6 in /lib. This is not correct. There must not be such a
556 link. The linker script with the above contents is placed in
557 /usr/lib which is enough for the linker.
560 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
561 [Q18] ``The prototypes for `connect', `accept', `getsockopt',
562 `setsockopt', `getsockname', `getpeername', `send',
563 `sendto', and `recvfrom' are different in GNU libc from
564 any other system I saw. This is a bug, isn't it?''
566 [A18] {UD} No, this is no bug. This version of the GNU libc already
567 follows the to-be-released POSIX.1g standard. In this standard
568 the type `size_t' is used for all parameters which describe a size.
569 So better change now.
571 This change is critical for system which have
572 sizeof (int) != sizeof (size_t)
576 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
577 [Q19] ``My XXX kernel emulates a floating-point coprocessor for me.
578 Should I enable --with-fp?''
580 [A19] {UD} As `configure --help' shows the default value is `yes' and
581 this should not be changed unless the FPU instructions would be
582 invalid. I.e., an emulated FPU is for the libc as good as a real one.
585 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
587 Answers were given by:
588 {UD} Ulrich Drepper, <drepper@cygnus.com>
589 {DMT} David Mosberger-Tang, <davidm@AZStarNet.com>
590 {RM} Roland McGrath, <roland@gnu.ai.mit.edu>