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Estimated hours taken: 0.25 tools/bindist.README.Linux: Add a version of the README.Linux modified for the binary release (I just removed the stuff about how to get the source distribution to compile with libc 6).
38 lines
1.9 KiB
Plaintext
38 lines
1.9 KiB
Plaintext
Mercury has only been ported to Linux/x86, not to Linux/Alpha
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Linux/PowerPC, Linux/m68k, etc. Those other ports should
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not be difficult, but this file documents just the Linux/x86 port.
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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 --cflags -DPIC_REG' and link with `ml --mercury-libs shared'
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or add `MGNUCFLAGS=-DPIC_REG' and `MLFLAGS=--mercury-libs shared'
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to your Mmake file.
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Mercury code compiled with `-DPIC_REG' or `-fpic' has what we shall call
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"PIC linkage", whereas Mercury code compiled without these options has
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"non-PIC linkage". The static version of the Mercury libraries has
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non-PIC linkage, while the shared version has PIC linkage.
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Be very careful that you do not try to link Mercury code
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with PIC linkage and Mercury code with non-PIC linkage into the same
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executable, otherwise your code will *almost certainly crash*.
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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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