GC on EWS4800

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1. About EWS4800

 EWS4800 is a 32/64-bit workstation.

     Vendor: NEC Corporation

     OS: UX/4800 R9.* - R13.* (SystemV R4.2)

     CPU: R4000, R4400, R10000 (MIPS)

2. Compiler

 32-bit:

   Use ANSI C compiler.

     CC = /usr/abiccs/bin/cc

 64-bit:

   Use the 64-bit ANSI C compiler.

     CC = /usr/ccs64/bin/cc

     AR = /usr/ccs64/bin/ar

3. ELF file format

   *** Caution: The following information is empirical. ***

 32-bit:

   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.

 64-bit:

   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

When using the new "configure; make" build process, please

run configure with the --disable-shared option.  "Make check" does not

yet pass with dynamic libraries.  The reasons for that are not yet

understood.  (HB, paraphrasing message from Hironori SAKAMOTO.)