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From: Jonathan Nieder <jrnieder-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: linux-man-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: Petr Baudis <pasky-AlSwsSmVLrQ@public.gmane.org>,
	Aurelien Jarno <aurelien-rXXEIb44qovR7s880joybQ@public.gmane.org>,
	Reuben Thomas <rrt-0NV8xZLkR+A@public.gmane.org>
Subject: [PATCH 4/6] ld.so.8: document Debian's /etc/ld.so.nohwcap extension
Date: Thu, 20 Oct 2011 02:14:24 -0500	[thread overview]
Message-ID: <20111020071424.GD11485@elie.hsd1.il.comcast.net> (raw)
In-Reply-To: <20111020070037.GA11392-E4JsH6yu/ca99If2fRKg35Ea+QML8DWm@public.gmane.org>

To avoid trouble when the generic version of libc has been upgraded
but some machine-specific versions have not, Ben Collins came up with
this hack to temporarily disable the feature of choosing which library
to load based on hardware capabilities.  It is just an internal
feature, but let's document it anyway to avoid people being confused
if Debian's custom ld.so(8) manpage gets replaced with an up-to-date
copy from man-pages.

Text from Aurelian Jarno's update to the Debian glibc package, r1812
(ld.so.8: Update the manpage, 2006-10-01).

Signed-off-by: Jonathan Nieder <jrnieder-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
Incidentally, is there some upstream-supported way to do this
(override LD_HWCAP_MASK using a file on the filesystem)?  How do other
distros address this problem (e.g., ABI mismatches between out-of-date
hwcap libs and the updated libnss) during upgrades?

 man8/ld.so.8 |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/man8/ld.so.8 b/man8/ld.so.8
index 6b5799b..a5ecc4b 100644
--- a/man8/ld.so.8
+++ b/man8/ld.so.8
@@ -382,6 +382,11 @@ libraries and an ordered list of candidate libraries.
 File containing a whitespace separated list of ELF shared libraries to
 be loaded before the program.
 .TP
+.I /etc/ld.so.nohwcap
+(Debian only, since glibc 2.2.93-1)
+When this file is present the dynamic linker will load the non-optimized version
+of a library, even if the CPU supports the optimized version.
+.TP
 .B lib*.so*
 shared libraries
 .PD
-- 
1.7.7

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  parent reply	other threads:[~2011-10-20  7:14 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-10-20  7:01 [PATCH/RFC 0/6] ld.so.8: some improvements from Debian Jonathan Nieder
     [not found] ` <20111020070037.GA11392-E4JsH6yu/ca99If2fRKg35Ea+QML8DWm@public.gmane.org>
2011-10-20  7:04   ` [PATCH 1/6] ld.so.8: clarify synopsis Jonathan Nieder
     [not found]     ` <20111020070412.GA11485-E4JsH6yu/ca99If2fRKg35Ea+QML8DWm@public.gmane.org>
2011-10-20 18:08       ` Mike Frysinger
     [not found]         ` <201110201408.34778.vapier-aBrp7R+bbdUdnm+yROfE0A@public.gmane.org>
2011-10-20 18:17           ` Reuben Thomas
     [not found]             ` <CAOnWdojdzzvBFnyE9njnZg+RFoaC8V-HGSnhiBhGeY-tQzCiig-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-10-20 18:18               ` Reuben Thomas
2011-10-20 18:26               ` Mike Frysinger
     [not found]                 ` <201110201426.07094.vapier-aBrp7R+bbdUdnm+yROfE0A@public.gmane.org>
2011-10-20 18:28                   ` Reuben Thomas
     [not found]                     ` <CAOnWdojWj5PYAp7ANX_qmvTJjR9EicSy0yG5LUTumOxQTpmQAQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-10-20 18:51                       ` Mike Frysinger
2011-10-20 18:39           ` Jonathan Nieder
2011-10-20  7:06   ` [PATCH 2/6] ld.so.8: move important information toward the top Jonathan Nieder
2011-10-20  7:09   ` [PATCH 3/6] ld.so.8: document LD_ASSUME_KERNEL Jonathan Nieder
2011-10-20  7:14   ` Jonathan Nieder [this message]
     [not found]     ` <20111020071424.GD11485-E4JsH6yu/ca99If2fRKg35Ea+QML8DWm@public.gmane.org>
2011-10-20 18:11       ` [PATCH 4/6] ld.so.8: document Debian's /etc/ld.so.nohwcap extension Mike Frysinger
     [not found]         ` <201110201411.03656.vapier-aBrp7R+bbdUdnm+yROfE0A@public.gmane.org>
2011-10-21  5:30           ` Jonathan Nieder
2011-10-20  7:15   ` [PATCH 5/6] ld.so.8: document $PLATFORM and $LIB expansion Jonathan Nieder
     [not found]     ` <20111020071538.GE11485-E4JsH6yu/ca99If2fRKg35Ea+QML8DWm@public.gmane.org>
2011-10-20 18:16       ` Mike Frysinger
     [not found]         ` <201110201416.30351.vapier-aBrp7R+bbdUdnm+yROfE0A@public.gmane.org>
2011-10-21  5:25           ` Jonathan Nieder
     [not found]             ` <20111021052528.GF23372-E4JsH6yu/ca99If2fRKg35Ea+QML8DWm@public.gmane.org>
2011-12-11  3:16               ` Mike Frysinger
     [not found]                 ` <201112102216.34565.vapier-aBrp7R+bbdUdnm+yROfE0A@public.gmane.org>
2012-04-16 16:59                   ` Jonathan Nieder
2011-10-20  7:16   ` [PATCH 6/6] ld.so.8: document how hwcaps affect search path Jonathan Nieder
2011-11-07  8:41   ` [PATCH/RFC 0/6] ld.so.8: some improvements from Debian Reuben Thomas
2012-04-16  7:26   ` Michael Kerrisk (man-pages)
     [not found]     ` <CAKgNAkgbcL3deJ4x0DEV==vtiAmYie7+Gw+c=K_dAJhWE4va1Q-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-04-16 16:58       ` Jonathan Nieder
2012-04-16 17:19         ` Michael Kerrisk (man-pages)
     [not found]           ` <CAKgNAkj0BAKbP6SrohCEG+eeEAZAYkJ6NA9Jvi0hS2j3e19mmg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-04-16 17:24             ` Jonathan Nieder
2012-04-16 18:07               ` Michael Kerrisk (man-pages)
     [not found]                 ` <CAKgNAkggZ1EZyBkkkd4xmJnjt-_kw=F_xb81+--gpQztvyD8oA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-04-16 18:23                   ` Jonathan Nieder
2012-04-16 19:03                   ` [PATCH v2] ld.so.8: Document effect of hwcaps on search path Jonathan Nieder
2012-04-16 19:19                     ` Michael Kerrisk (man-pages)
     [not found]                       ` <CAKgNAkjfcbiDiGqd1PNpdPcUTQBd+8qyrWZj3D6hnzU5vZdecA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-04-16 19:27                         ` [PATCH v3] " Jonathan Nieder
2012-04-16 20:00                           ` Michael Kerrisk (man-pages)
     [not found]                             ` <CAKgNAkiZT4oUV6WKprpc2DWdJMSVQaOEyqL9VmsBub7TMW6HKw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-04-16 20:13                               ` Jonathan Nieder
2012-04-16 20:29                                 ` Michael Kerrisk (man-pages)
2012-04-16 20:39                           ` Michael Kerrisk (man-pages)
2012-04-21 18:04                           ` Mike Frysinger

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