I need help with gc

Fri Apr 26 03:00:00 GMT 2002

Hi!
i get a SegFault on Linux in 
#0 GC_mark_from (mark_stack_top=0x85c5000, mark_stack=0x85c5000,
mark_stack_limit=0x85cd000) at ../../../gcc-3.1-20020423/boehm-gc/mark.c:654
654 deferred = *limit;
(gdb) p limit
1ドル = (word *) 0x8569048
This is an address inside a fortran common block which is layed out like this:
 COMMON /BLANK/ NODPRE,NODPLC,NODPST
 INTEGER NODPRE(4096), NODPLC(2048), NODPST(2048)
 REAL*8 VALUE(1024)
 COMPLEX*16 ZVALUE(512)
 CHARACTER CHRARR(8192)
 EQUIVALENCE (VALUE(1),NODPLC(1),ZVALUE(1),CHRARR(1))
C
and also addressed from C by
extern struct
{
 int padding_pre[4096];
 union
 {
 char carray[8192];
 int iarray[2048];
 double darray[1024];
 Complex zarray[512];
 } userdata;
 int padding_post[2048];
} blank_;
In the application blank.padding_pre = 0x8566220.
Thus limit is somewhere in the middle of NODPRE or blank_padding_pre.
Is this an error? 
I found that because i mprotected a region around NODPLC / blank_userdata
 with PROT_NONE in order to catch errors in my code.
The full stack frame is this:
#0 GC_mark_from (mark_stack_top=0x85c5000, mark_stack=0x85c5000, mark_stack_limit=0x85cd000) at ../../../gcc-3.1-20020423/boehm-gc/mark.c:654
#1 0x40642ad2 in GC_mark_some (cold_gc_frame=0x8568e50 "") at ../../../gcc-3.1-20020423/boehm-gc/mark.c:289
#2 0x4063f025 in GC_stopped_mark (stop_func=0x8568e50 <blank_+11312>) at ../../../gcc-3.1-20020423/boehm-gc/alloc.c:489
#3 0x4063ed9c in GC_try_to_collect_inner (stop_func=0x4063e950 <GC_never_stop_func>) at ../../../gcc-3.1-20020423/boehm-gc/alloc.c:350
#4 0x40645105 in GC_init_inner () at ../../../gcc-3.1-20020423/boehm-gc/misc.c:673
#5 0x406410d4 in GC_init_gcj_malloc (mp_index=0, mp=0x1fc) at ../../../gcc-3.1-20020423/boehm-gc/gcj_mlc.c:60
#6 0x4063e452 in _Jv_InitGC() () at ../../../gcc-3.1-20020423/libjava/boehm.cc:465
#7 0x405ca741 in _Jv_CreateJavaVM(void*) () at ../../../gcc-3.1-20020423/libjava/prims.cc:892
#8 0x405cd665 in JNI_CreateJavaVM (vm=0x1fc, penv=0x1fc, args=0xbfff9cf0) at ../../../gcc-3.1-20020423/libjava/jni.cc:2262
#9 0x0805cbf6 in loadJVM () at c_code/vti.c:660
....
Is this behaviour correct and i just cannot mprotect static data and use the gc or is it an error?
Thanks for any help,
Martin.
-- 
The early bird catches the worm. If you want something else for 
breakfast, get up late