diff options
Diffstat (limited to 'ld/ld.texinfo')
| -rw-r--r-- | ld/ld.texinfo | 52 |
1 files changed, 50 insertions, 2 deletions
diff --git a/ld/ld.texinfo b/ld/ld.texinfo index 592e38c..6c74ff5 100644 --- a/ld/ld.texinfo +++ b/ld/ld.texinfo @@ -1,7 +1,7 @@ \input texinfo @setfilename ld.info @c Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, -@c 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 +@c 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 @c Free Software Foundation, Inc. @syncodeindex ky cp @c man begin INCLUDE @@ -6710,7 +6710,9 @@ optimization. @cindex PowerPC64 multi-TOC @kindex --no-multi-toc @item --no-multi-toc -By default, PowerPC64 GCC generates code for a TOC model where TOC +If given any toc option besides @code{-mcmodel=medium} or +@code{-mcmodel=large}, PowerPC64 GCC generates code for a TOC model +where TOC entries are accessed with a 16-bit offset from r2. This limits the total TOC size to 64K. PowerPC64 @command{ld} extends this limit by grouping code sections such that each group uses less than 64K for its @@ -6719,6 +6721,52 @@ calls. @command{ld} does not split apart input sections, so cannot help if a single input file has a @code{.toc} section that exceeds 64K, most likely from linking multiple files with @command{ld -r}. Use this option to turn off this feature. + +@cindex PowerPC64 TOC sorting +@kindex --no-toc-sort +@item --no-toc-sort +By default, @command{ld} sorts TOC sections so that those whose file +happens to have a section called @code{.init} or @code{.fini} are +placed first, followed by TOC sections referenced by code generated +with PowerPC64 gcc's @code{-mcmodel=small}, and lastly TOC sections +referenced only by code generated with PowerPC64 gcc's +@code{-mcmodel=medium} or @code{-mcmodel=large} options. Doing this +results in better TOC grouping for multi-TOC. Use this option to turn +off this feature. + +@cindex PowerPC64 PLT stub alignment +@kindex --plt-align +@kindex --no-plt-align +@item --plt-align +@itemx --no-plt-align +Use these options to control whether individual PLT call stubs are +aligned to a 32-byte boundary, or to the specified power of two +boundary when using @code{--plt-align=}. By default PLT call stubs +are packed tightly. + +@cindex PowerPC64 PLT call stub static chain +@kindex --plt-static-chain +@kindex --no-plt-static-chain +@item --plt-static-chain +@itemx --no-plt-static-chain +Use these options to control whether PLT call stubs load the static +chain pointer (r11). @code{ld} defaults to not loading the static +chain since there is never any need to do so on a PLT call. + +@cindex PowerPC64 PLT call stub thread safety +@kindex --plt-thread-safe +@kindex --no-plt-thread-safe +@item --plt-thread-safe +@itemx --no-thread-safe +With power7's weakly ordered memory model, it is possible when using +lazy binding for ld.so to update a plt entry in one thread and have +another thread see the individual plt entry words update in the wrong +order, despite ld.so carefully writing in the correct order and using +memory write barriers. To avoid this we need some sort of read +barrier in the call stub, or use LD_BIND_NOW=1. By default, @code{ld} +looks for calls to commonly used functions that create threads, and if +seen, adds the necessary barriers. Use these options to change the +default behaviour. @end table @ifclear GENERIC |