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