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Estimated hours taken: 1 scripts/ml.in: Make static linking the default on FreeBSD, since shared linking doesn't work. README.FreeBSD: Document that shared libraries are not supported on FreeBSD. Add some hints about what would need to be done to make them work.
57 lines
2.2 KiB
Plaintext
57 lines
2.2 KiB
Plaintext
For FreeBSD, the Boehm conservative garbage collector does not yet support
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shared libraries. So Mercury does not yet support shared libraries on FreeBSD,
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except in the (not very useful) case where you compile with GC disabled,
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e.g. using the option `--gc none'.
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The rest of this file contains some hints for eager FreeBSD hackers
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about what would need to be done to make the Boehm collector support
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shared libraries on FreeBSD.
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--------------------
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The basic problem is that on FreeBSD the conservative collector does not
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scan the memory regions that contain global variables from dynamically linked
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shared object files.
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First, check the `recent_changes' file at
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<http://reality.sgi.com/boehm/gc_source/> to see if someone else
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has already solved the problem.
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In order to support dynamic linking, I think you need to implement the
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GC_register_dynamic_libraries() function in boehm_gc/dyn_load.c.
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This function needs to call
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GC_add_root(low_address, high_plus_one_address, TRUE)
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for every memory region in dynamically loaded code that needs to be
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scanned by the collector, so that the collector can scan global
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variables defined in shared libraries.
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If FreeBSD uses ELF and supports ELF in exactly the same way that Linux
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does, then you could try the following patch, which just enables the Linux
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code in the FreeBSD case. But most likely there are some differences
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between FreeBSD and Linux in this respect, so this will probably not work
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as is -- you should consider this just a starting point.
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Read the comments at the top of dyn_load.c for more details.
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--- dyn_load.c Mon Aug 31 15:05:05 1998
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+++ dyn_load.c.new Wed Jun 16 22:58:48 1999
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@@ -260,7 +260,7 @@
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# endif /* !USE_PROC ... */
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# endif /* SUNOS */
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-#if defined(LINUX) && defined(__ELF__) || defined(SCO_ELF)
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+#if defined(LINUX) && defined(__ELF__) || defined(SCO_ELF) || defined(FREEBSD)
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/* Dynamic loading code for Linux running ELF. Somewhat tested on
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* Linux/x86, untested but hopefully should work on Linux/Alpha.
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--- config.h Wed Oct 28 10:16:49 1998
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+++ config.h.new Wed Jun 16 23:08:56 1999
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@@ -699,6 +699,7 @@
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# ifdef FREEBSD
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# define OS_TYPE "FREEBSD"
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# define MPROTECT_VDB
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+# define DYNAMIC_LOADING
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# endif
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# ifdef NETBSD
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# define OS_TYPE "NETBSD"
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