From 49a086299e047b18280457b654790ef4a2e5abfa Mon Sep 17 00:00:00 2001 From: Samuel Thibault Date: Wed, 18 Feb 2015 00:58:35 +0100 Subject: Revert "rename open_issues.mdwn to service_solahart_jakarta_selatan__082122541663.mdwn" This reverts commit 95878586ec7611791f4001a4ee17abf943fae3c1. --- open_issues/glibc_madvise_vs_static_linking.mdwn | 48 ++++++++++++++++++++++++ 1 file changed, 48 insertions(+) create mode 100644 open_issues/glibc_madvise_vs_static_linking.mdwn (limited to 'open_issues/glibc_madvise_vs_static_linking.mdwn') diff --git a/open_issues/glibc_madvise_vs_static_linking.mdwn b/open_issues/glibc_madvise_vs_static_linking.mdwn new file mode 100644 index 00000000..4af41931 --- /dev/null +++ b/open_issues/glibc_madvise_vs_static_linking.mdwn @@ -0,0 +1,48 @@ +[[!meta copyright="Copyright © 2010, 2011, 2012, 2013 Free Software Foundation, +Inc."]] + +[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable +id="license" text="Permission is granted to copy, distribute and/or modify this +document under the terms of the GNU Free Documentation License, Version 1.2 or +any later version published by the Free Software Foundation; with no Invariant +Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license +is included in the section entitled [[GNU Free Documentation +License|/fdl]]."]]"""]] + +[[!tag open_issue_glibc]] + +[[!sourceware_PR 4822]]. + + $ echo 'int main() {}' | gcc -o /dev/null -static -x c - + /usr/lib/gcc/i486-gnu/4.4.5/../../../libcrt.a(malloc.o): In function `_int_free': + (.text+0xdc3): warning: warning: madvise is not implemented and will always fail + +This is correct, but it does confuse GNU Autoconf, for example, which then +thinks that static linking is not supported and sets a flag accordingly, which +luckly no / not many packages use. + +*This call does not influence the semantics of the application (except in the +case of MADV_DONTNEED), but may influence its performance. The kernel is free +to ignore the advice.* (`man madvise`), so we may simply want to turn it into a +no-op in glibc, avoiding the link-time warning. + +GCC c5db973fdab3db3e13db575e5650c0bcfd3630f4 (2011-10-17) makes use of this. +As we now export the symbol (and `MADV_DONTNEED`, too), GCC will no longer +`munmap` pages, but will keep them mapped for later re-use. This may increase +memory usage. The discussion in [[!message-id +"20120720162519.734e02eb@spoyarek"]] touches related topics. + +2011-07: This is what Samuel has [done for Debian +glibc](http://anonscm.debian.org/viewvc/pkg-glibc/glibc-package/trunk/debian/patches/hurd-i386/local-madvise_warn.diff). + + +# IRC, freenode, #hurd, 2012-02-16 + + youpi: With Roland's fix the situation will be that just using + gcc -static doesn't emit the stub warning, but still will do so in case + that the source code itself links in madvise. Is this acceptable for + you/Debian/...? + packages with -Werror will still bug out + not that I consider -Werror to be a good idea, though :) + youpi: Indeed. Compiler warnings can be caused by all kinds of + things. -Werror is good for development, but not for releases. -- cgit v1.2.3