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* FAQ.in: Describe why glibc needs to be compiled with 
optimization.
This commit is contained in:
Andreas Jaeger 2008-02-22 09:57:19 +00:00
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FAQ.in
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@ -387,6 +387,31 @@ yourself. Please remember that for each architecture there may be various
patches required to get glibc HEAD into a runnable state. The best course
of action is to determine if you have all the required patches.
?? Why do I get:
`#error "glibc cannot be compiled without optimization"',
when trying to compile GNU libc with GNU CC?
{AJ,CO} There are a couple of reasons why the GNU C library will not work
correctly if it is not complied with optimzation.
In the early startup of the dynamic loader (_dl_start), before
relocation of the PLT, you cannot make function calls. You must inline
the functions you will use during early startup, or call compiler
builtins (__builtin_*).
Without optimizations enabled GNU CC will not inline functions. The
early startup of the dynamic loader will make function calls via an
unrelocated PLT and crash.
Without auditing the dynamic linker code it would be difficult to remove
this requirement.
Another reason is that nested functions must be inlined in many cases to
avoid executable stacks.
In practice there is no reason to compile without optimizations, therefore
we require that GNU libc be compiled with optimizations enabled.
? Installation and configuration issues
?? Can I replace the libc on my Linux system with GNU libc?
@ -1685,6 +1710,7 @@ Answers were given by:
{AO} Alexandre Oliva, <aoliva@redhat.com>
{BH} Bruno Haible, <haible@clisp.cons.org>
{SM} Steven Munroe, <sjmunroe@us.ibm.com>
{CO} Carlos O'Donell, <carlos@systemhalted.org>
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