From c49e86f103be3db22cbb3eee5c6299a0a8ac401b Mon Sep 17 00:00:00 2001 From: Andreas Jaeger Date: Fri, 22 Feb 2008 09:57:19 +0000 Subject: [PATCH] [BZ #5012] * FAQ.in: Describe why glibc needs to be compiled with optimization. --- FAQ.in | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/FAQ.in b/FAQ.in index d0b2805..a5c7123 100644 --- a/FAQ.in +++ b/FAQ.in @@ -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, {BH} Bruno Haible, {SM} Steven Munroe, +{CO} Carlos O'Donell, Local Variables: mode:outline -- 2.7.4