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Estimated hours taken: 0.25 README.Linux-Alpha: Document a patch needed to make things work on Linux/Alpha. README.Linux: Point to README.Linux-Alpha.
65 lines
3.1 KiB
Plaintext
65 lines
3.1 KiB
Plaintext
This file documents just the Linux/x86 port.
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For the Linux/PowerPC port, see README.Linux-PPC.
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For the Linux/Alpha port, see README.Linux-Alpha.
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(Ports to Linux on other architecures have not yet
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been attempted, but should not be difficult.)
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On Linux with a.out, shared libraries are not supported.
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If you still have an old a.out system, the auto-configuration might
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wrongly assume your Linux system uses ELF; if that happens, you will you
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have to manually edit the EXT_FOR_SHARED_LIB variable in Mmake.common.
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There are some incompatibilities in different kernel versions and libc
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versions to do with the handling of signals. We had added some
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autoconfiguration code to try to detect which header files need to be
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included, but if you have trouble compiling boehm_gc/os_dep.c, try
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applying the patch below (and send us a bug report if you can).
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Just type `patch boehm_gc/os_dep.c < README.Linux'.
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On Linux with ELF, shared libraries are supported. However, ELF shared
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libraries require position-independent code, and (partly due to
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limitations in our current compilation technology, but partly due to
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limitations in the x86 architecture) this is quite costly for Mercury --
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probably considerably more costly than it is for C.
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Nevertheless, since shared libraries reduces disk usage, improve link
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times, and allow run-time sharing of the Mercury libraries between
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different applications, using them is a good idea.
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Currently the default is that programs do *not* use the Mercury shared
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libraries. (Probably it ought to be the other way around, but that
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happened to be a little bit harder to implement. We may change this in
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a future release.)
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To use the shared libraries, you must compile your program with
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`mmc --pic-reg' and link with `ml --mercury-libs shared'
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or add `MGNUCFLAGS=--pic-reg' and `MLFLAGS=--mercury-libs shared'
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to your Mmake file.
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Mercury code compiled with `--pic-reg' or with gcc's `-fpic' option has
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what we shall call "PIC linkage", whereas Mercury code compiled without
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these options has "non-PIC linkage". The static version of the Mercury
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libraries has non-PIC linkage, while the shared version has PIC linkage.
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Be careful that you do not try to link Mercury code with PIC linkage and
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Mercury code with non-PIC linkage into the same executable, otherwise you
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will probably get an obscure link error about `MR_grade_...' undefined
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or `MR_runtime_grade' multiply defined.
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(The reason for this is that standard non-PIC Mercury code uses the
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`ebx' register in ways that are incompatible with its uses as the global
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offset table pointer register in PIC code. If only the Intel
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architecture wasn't so register-starved, we wouldn't need to use `ebx',
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and then PIC and non-PIC code could be mixed without any problems.)
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--------------------
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--- os_dep.c Tue Feb 10 15:37:42 1998
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+++ new/os_dep.c Tue Feb 10 16:04:24 1998
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@@ -38,6 +38,7 @@
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/* 10-Feb-1998 Modified to use autoconf to handle this for */
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/* Mercury -- Tyson Dowd <trd@cs.mu.oz.au> */
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# ifdef MERCURY_LINUX_NEED_ASM_SIGCONTEXT
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+/*** # include <asm/sigcontext.h> ***/
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# include <asm/sigcontext.h>
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# endif
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# endif
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