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76 lines
1.8 KiB
Plaintext
76 lines
1.8 KiB
Plaintext
GC on EWS4800
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1. About EWS4800
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EWS4800 is 32bit/64bit workstation.
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Vender: NEC Corporation
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OS: UX/4800 R9.* - R13.* (SystemV R4.2)
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CPU: R4000, R4400, R10000 (MIPS)
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2. Compiler
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32bit:
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Use ANSI C compiler.
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CC = /usr/abiccs/bin/cc
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64bit:
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Use 64bit ANSI C compiler.
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CC = /usr/ccs64/bin/cc
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AR = /usr/ccs64/bin/ar
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3. ELF file format
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*** Caution: The following infomation is empirical. ***
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32bit:
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ELF file has an unique format. (See a.out(4) and end(3C).)
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&_start
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: text segment
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&etext
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DATASTART
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: data segment (initialized)
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&edata
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DATASTART2
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: data segment (uninitialized)
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&end
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Here, DATASTART and DATASTART2 are macros of GC, and are defined as
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the following equations. (See include/private/gcconfig.h.)
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The algorithm for DATASTART is similar with the function
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GC_SysVGetDataStart() in os_dep.c.
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DATASTART = ((&etext + 0x3ffff) & ~0x3ffff) + (&etext & 0xffff)
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Dynamically linked:
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DATASTART2 = (&_gp + 0x8000 + 0x3ffff) & ~0x3ffff
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Statically linked:
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DATASTART2 = &edata
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GC has to check addresses both between DATASTART and &edata, and
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between DATASTART2 and &end. If a program accesses between &etext
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and DATASTART, or between &edata and DATASTART2, the segmentation
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error occurs and the program stops.
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If a program is statically linked, there is not a gap between
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&edata and DATASTART2. The global symbol &_DYNAMIC_LINKING is used
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for the detection.
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64bit:
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ELF file has a simple format. (See end(3C).)
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_ftext
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: text segment
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_etext
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_fdata = DATASTART
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: data segment (initialized)
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_edata
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_fbss
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: data segment (uninitialized)
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_end = DATAEND
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--
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Hironori SAKAMOTO <hsaka@mth.biglobe.ne.jp>
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