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