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53 lines
1.9 KiB
Plaintext
53 lines
1.9 KiB
Plaintext
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The GAS Configuration Plan
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Theory:
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The goal of the new configuration scheme is to bury all object format,
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target processor, and host machine dependancies in object, target, and
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host specific files. That is, to move all #ifdef's out of the gas
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common code.
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Here's how it works. There is a .h and a .c file for each object file
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format, a .h and a .c file for each target processor, and a .h for
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each host. config.gas creates {sym}links in the current directory to
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the appropriate files in the config directory. config.gas also serves
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as a list of triplets {host, target, object-format} that have been
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tested at one time or another. I also recommend that config.gas be
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used to document triplet specific notes as to purpose of the triplet,
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etc.
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Implementation:
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host.h is a {sym}link to .../config/xm-yourhost.h. It is intended to
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be used to hide host compiler, system header file, and system library
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differences between host machines. If your host needs actual c source
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files, then either: these are generally useful functions, in which
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case you should probably build a local library outside of the gas
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source tree, or someone, perhaps me, is confused about what is needed
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by different hosts.
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obj-format.h is a {sym}link to .../config/obj-something.h. It is intended
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All gas .c files include as.h.
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as.h #define's "gas", includes host.h, defines a number of gas
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specific structures and types, and then includes tp.h, obj.h, and
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target-environment.h.
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target-environment.h defines a target environment specific
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preprocessor flag, eg, TE_SUN, and then includes obj-format.h.
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obj-format.h defines an object format specific preprocessor flag, eg,
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OBJ_AOUT, OBJ_BOUT, OBJ_COFF, includes "target-processor.h", and then
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defines the object specific macros, functions, types, and structures.
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target-processor.h
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target-processor.
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Porting:
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There appear to be four major types of ports; new hosts, new target
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processors, new object file formats, and new target environments.
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