55 lines
1.9 KiB
Plaintext
55 lines
1.9 KiB
Plaintext
$NetBSD: README.dynamic,v 1.3 1999/04/27 16:08:40 cgd Exp $
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Dynamically linked programs are supported by NetBSD's Digital UNIX
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(formerly DEC OSF/1) emulation. The OSF/1 dynamic linker scheme is
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described in fair detail in:
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%A Larry W. Allen
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%A Harminder G. Singh
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%A Kevin G. Wallace
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%A Melanie B. Weaver
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%T Program Loading in OSF/1
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%P 145-160
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%I USENIX
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%B USENIX Conference Proceedings
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%D January 21-25, 1991
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%C Dallas, TX
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%W Open Software Foundation
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Additionally, the object file formats in use are described in the
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Digital UNIX _Assembly Language Programmer's Guide_ which can be
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found (among other places) on a version-specific page off of:
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http://www.unix.digital.com/faqs/publications/pub_page/doc_list.html
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Finally, the actual representation of Auxiliary Vectors came from information
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in the Digital UNIX auxv.h header file.
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There are at least two potential issues with the implementation as it
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currently exists:
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1. exec_with_loader() is not emulated.
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Most uses of dynamically linked programs come through execve()
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and use the default loader (/sbin/loader). In Digital UNIX
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(and OSF/1) you can also force a specific loader to always be
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invoked to load an executable by using the exec_with_loader()
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system call. Few, if any, programs use this feature.
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2. It is not immediately obvious that the right values are used for
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text and data locations when invoking a dynamically linked executable.
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The text and data sections, and the break, are set up as if
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/sbin/loader itself had been executed. It's not clear that this
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is correct, but /sbin/loader seems to expect that at least the
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break will be set up this way.
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This has certain implications for the way mmap() behaves. See
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the comment in the osf1_mmap() function in osf1_misc.c.
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3. The stack location is used is the normal NetBSD/alpha stack location.
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No attempt is made to put the stack in the place where
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Digital UNIX would normally put it. This may confuse some
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programs.
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