The following adds an entry to the FAQ to mention why optimization is needed for compiling glibc. Ok to commit? Andreas 2007-10-27 Andreas Jaeger , Carlos O'Donell [BZ #5012] * FAQ.in: Describe why glibc needs to be compiled with optimization. ============================================================ Index: FAQ.in --- FAQ.in 8 Apr 2005 20:59:50 -0000 1.137 +++ FAQ.in 27 Oct 2007 15:14:50 -0000 @@ -387,6 +387,32 @@ yourself. Please remember that for each 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 +1711,7 @@ Answers were given by: {AO} Alexandre Oliva, {BH} Bruno Haible, {SM} Steven Munroe, +{CO} Carlos O'Donell, Local Variables: mode:outline -- Andreas Jaeger, Director Platform / openSUSE, aj@suse.de SUSE LINUX Products GmbH, GF: Markus Rex, HRB 16746 (AG Nürnberg) Maxfeldstr. 5, 90409 Nürnberg, Germany GPG fingerprint = 93A3 365E CE47 B889 DF7F FED1 389A 563C C272 A126