Re: [BUGS] My investigations of the postmaster Bus error

Hey Martin,

I've been playing with the MIPS machine a little and still haven't found
any _obvious_ cause for the problem. However I suspect that it may be
related to unaligned memory access, which _I think_ results in a SIGBUS
on MIPS. I haven't found any documentation on MIPS that would confirm
this however. I'm not sure exactly how would this by worked around; it
occurs to me that we'd have to change config_real to look like

struct config_real
{
enum {
struct config_generic gen;
double dummy;
} field1;

/* these fields must be set correctly in initial value: */
/* (all but reset_val are constants) */
double *variable;
...
}

though I'm not sure and I haven't tested it. (Of course a working patch
needs to change a few more places.) I'll do some more experiments and
I'll let you know.

mpitt(at)reset:/tmp/pgsql8.0.4$ gdb bin/postgres
GNU gdb 6.3-debian
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This GDB was configured as "mips-linux"...Using host libthread_db library "/lib/libthread_db.so.1".

(gdb) set args -boot
(gdb) run
Starting program: /tmp/pgsql8.0.4/bin/postgres -boot

Program received signal SIGBUS, Bus error.
0x00818c38 in InitializeGUCOptions () at guc.c:2360
2360 *conf->variable = conf->reset_val;
(gdb) bt
#0 0x00818c38 in InitializeGUCOptions () at guc.c:2360
#1 0x004a8fc0 in BootstrapMain (argc=2, argv=0x10053998) at bootstrap.c:244
#2 0x005f4dc4 in main (argc=2, argv=0x10053998) at main.c:296
(gdb) print *conf
$1 = {gen = {name = 0x8c4484 "geqo_selection_bias", context = PGC_USERSET, group = QUERY_TUNING_GEQO,
short_desc = 0x8c4498 "GEQO: selective pressure within the population.", long_desc = 0x0, flags = 0, vartype = PGC_REAL,
status = 0, reset_source = PGC_S_DEFAULT, tentative_source = PGC_S_DEFAULT, source = PGC_S_DEFAULT, stack = 0x0},
variable = 0x100136d2, reset_val = 2, min = 1.5, max = 2, assign_hook = 0, show_hook = 0, tentative_val = 0}

--
Alvaro Herrera http://www.amazon.com/gp/registry/CTMLCN8V17R4
"La grandeza es una experiencia transitoria. Nunca es consistente.
Depende en gran parte de la imaginación humana creadora de mitos"
(Irulan)