Re: I can't generate a kernel crash core.

[christos%astron.com@localhost (Christos Zoulas)]

In article <CAGisHBdzjDazW7H_bcDmQ=aERqcuc=QDYVrkj7vQFQHUqY7v6Q%mail.gmail.com@localhost>,
Jose Luis Rodriguez Garcia  <joseyluis%gmail.com@localhost> wrote:
>I have been debuging this problem with gdb and printfs in the source
>for locate the path.
>
>I have found it fails in:
>
>arch/amd64/amd64/machdep.c:dodumpsys does: psize = bdev_size(dumpdev);
>kern/subr_devsw.c:bdev_size calls rv = (*d->d_psize)(dev)
>In my case the dev has major 0 and minor 1
>(gdb) print bdevsw[0].d_psize
>$1 = (int (*)(dev_t)) 0xffffffff80a0ad60 <wdsize>
>
>then d->d_psize is the function wdsize
>
>dev/ata/wd.c:wdsize does wd = device_lookup_private(&wd_cd, WDUNIT(dev));
>kern/subr_autoconf.c:device_lookup_private does  return
>device_private(device_lookup(cd, unit));
>kern/subr_autoconf.c:device_lookup fails and returns NULL. This is in
>the sentence:
>
>
>else if ((dv = cd->cd_devs[unit]) != NULL && dv->dv_del_gen != 0)
> dv = NULL;
>
>config_alldevs_unlock(s);
>
> return dv;
>
>because cd->cd_devs[unit]) is null.
>
>I have checked these values with printf in the function and these are
>(executing a reboot -d):
>unit: 0
>cd->cd_ndevs: 4
>dv is assigned NULL in the asignement: dv = cd->cd_devs[unit])
>
>If I check these values when the system is running cd->cd_devs[unit] isn't NULL.
>(gdb) print wd_cd->cd_devs[0]
>$23 = (device_t) 0xfffffe8107cc6408
>(gdb) print (*wd_cd->cd_devs[0]).dv_del_gen
>$24 = 0
>
>It seems that in the ordered shutdow process this structure
>(cd->cd_devs[unit] is destroyed, and the dump fails.
>
>
>
>This is the log from dmesg. It says "dump area unavailable"
>(file src/sys/arch/amd64/amd64/machdep.c line 1156)
>.....
>wd0: detached
>atabus0: detached
>
>dumping to dev 0,1 (offset=8410383, size=1046094):
>dump area unavailable
>rebooting...
>
>The swap device configuration seems ok:
>pc2$ swapctl -z
>dump device is wd0b
>
>

Perhaps we should prevent the dumping device from being detatched if RB_DUMP
is set.

christos