With your path=2C i was able to = capture crash dump. This patch should be added to mainstream bsd to help pe= ople with capture boot panics.

Here is beginning of core.txt file. L= et me know if you need more info.

Trying to mount root from zfs:root= []...

Fatal double fault:
eip =3D 0xc0cb801e
esp =3D 0xd93eff= 98
ebp =3D 0xd93f0300
cpuid =3D 0=3B apic id =3D 00
panic: double = fault
cpuid =3D 0
KDB: enter: panic

Reading symbols from /boot= /kernel/zfs.ko.symbols...done.
Loaded symbols for /boot/kernel/zfs.ko.sy= mbols
Reading symbols from /boot/kernel/krpc.ko.symbols...done.
Loade= d symbols for /boot/kernel/krpc.ko.symbols
Reading symbols from /boot/ke= rnel/opensolaris.ko.symbols...done.
Loaded symbols for /boot/kernel/open= solaris.ko.symbols
Reading symbols from /boot/kernel/if_vmx.ko.symbols..= .done.
Loaded symbols for /boot/kernel/if_vmx.ko.symbols
Reading symb= ols from /boot/kernel/cc_hd.ko.symbols...done.
Loaded symbols for /boot/= kernel/cc_hd.ko.symbols
Reading symbols from /boot/kernel/h_ertt.ko.symb= ols...done.
Loaded symbols for /boot/kernel/h_ertt.ko.symbols
#0 = =3B doadump (textdump=3D0) at pcpu.h:233
233 =3B =3B =3B&nbs= p=3B pcpu.h: No such file or directory.
=3B =3B =3B =3B= =3B =3B =3B in pcpu.h
(kgdb) #0 =3B doadump (textdump= =3D0) at pcpu.h:233
#1 =3B 0xc04c87d1 in db_dump (dummy=3D-106684713= 9=2C dummy2=3D0=2C dummy3=3D-1=2C
=3B =3B =3B dummy4=3D0xc0= a808b4 "") at /usr/src/sys/ddb/db_command.c:543
#2 =3B 0xc04c82cb in= db_command (cmd_table=3D<=3Bvalue optimized out>=3B)
=3B = =3B =3B at /usr/src/sys/ddb/db_command.c:449
#3 =3B 0xc04c8010 i= n db_command_loop () at /usr/src/sys/ddb/db_command.c:502
#4 =3B 0xc= 04ca8a1 in db_trap (type=3D<=3Bvalue optimized out>=3B=2C
=3B&n= bsp=3B =3B code=3D<=3Bvalue optimized out>=3B) at /usr/src/sys/ddb/= db_main.c:231
#5 =3B 0xc0693bd4 in kdb_trap (type=3D<=3Bvalue opti= mized out>=3B=2C
=3B =3B =3B code=3D<=3Bvalue optimized= out>=3B=2C tf=3D<=3Bvalue optimized out>=3B)
=3B =3B&nbs= p=3B at /usr/src/sys/kern/subr_kdb.c:656
#6 =3B 0xc093918f in trap (= frame=3D<=3Bvalue optimized out>=3B)
=3B =3B =3B at /us= r/src/sys/i386/i386/trap.c:712
#7 =3B 0xc092336c in calltrap () at /= usr/src/sys/i386/i386/exception.s:170
#8 =3B 0xc069345d in kdb_enter= (why=3D0xc09a7ef8 "panic"=2C
=3B =3B =3B msg=3D<=3Bvalue= optimized out>=3B) at cpufunc.h:71
#9 =3B 0xc065710f in panic (fm= t=3D<=3Bvalue optimized out>=3B)
=3B =3B =3B at /usr/sr= c/sys/kern/kern_shutdown.c:823
#10 0xc0939acb in dblfault_handler () at = /usr/src/sys/i386/i386/trap.c:1072
#11 0xc0cb801e in vdev_queue_io_to_is= sue (vq=3D0xc46a4b00)
=3B =3B =3B at /usr/src/sys/modules/z= fs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_queue.c:471
#12= 0xc0cb7fb8 in vdev_queue_io (zio=3D0xc4855000)
=3B =3B =3B= at /usr/src/sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/z= fs/vdev_queue.c:744
#13 0xc0cd84ee in zio_vdev_io_start (ziop=3D<=3Bva= lue optimized out>=3B)
=3B =3B =3B at /usr/src/sys/module= s/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/zio.c:2607
#14 0x= c0cd4c18 in zio_execute (zio=3D0xc4855000)
=3B =3B =3B at /= usr/src/sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/zi= o.c:1350
#15 0xc0cb74e4 in vdev_mirror_io_start (zio=3D0xc4823894)
&n= bsp=3B =3B =3B at /usr/src/sys/modules/zfs/../../cddl/contrib/opens= olaris/uts/common/fs/zfs/vdev_mirror.c:284