From d6675bd3300d0efb6d301060a4a5c7ebd36446aa Mon Sep 17 00:00:00 2001 From: drepper Date: Thu, 29 Apr 1999 16:50:44 +0000 Subject: [PATCH] Add question about sigaltstack always failing. --- FAQ.in | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/FAQ.in b/FAQ.in index 1152b53e6d..0b950c81c5 100644 --- a/FAQ.in +++ b/FAQ.in @@ -1314,6 +1314,18 @@ interface. For compilation with the old API, has to be included (and not ) and you can link with either `-ldb1' or `-ldb' for either of the db formats. +?? Autoconf's AC_CHECK_FUNC macro reports that a function exists, but + when I try to use it, it always returns -1 and sets errno to ENOSYS. + +{ZW} You are using a 2.0 Linux kernel, and the function you are trying to +use is only implemented in 2.1/2.2. Libc considers this to be a function +which exists, because if you upgrade to a 2.2 kernel, it will work. One +such function is sigaltstack. + +Your program should check at runtime whether the function works, and +implement a fallback. Note that Autoconf cannot detect unimplemented +functions in other systems' C libraries, so you need to do this anyway. + ? Miscellaneous -- 2.11.0