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 On Sun, Jan 24, 2016 at 11:00 PM, Jose Luis Rodriguez Garcia <joseyl...@gmail.com> wrote: > If the kernel hash a panic, the dump is captured, etc. and it works ok > (kern.dump_on_panic=1). > > I can't generate a crash dump of a running system. > > > On Sun, Jan 24, 2016 at 10:28 PM, Jose Luis Rodriguez Garcia > <joseyl...@gmail.com> wrote: >> It is NetBSD 7.0 amd64 >> >> The swap size is 8 GB, and the memory of the PC is 4GB. >>