kern.panic_reboot_wait_time – no effect on KDB-less machine

Hello,

currently, I have one stable/12-i386 machine panicing as ESXi guest.

The kernel was built without KDB.  Hence, I set 
debug.debugger_on_panic=0 in loader.conf.

Additionally, I set kern.panic_reboot_wait_time=20

But after the panic, the memory is dumped to swap and an immediate 
reboot happens.
Far too quick to read a single word of the kernel message (1G RAM only, 
quick ssd swap).

How can I delay the auto-reboot?
Does kern.panic_reboot_wait_time only affect KDB behaviour?

Thanks,

-harry

P.S.: I guess the following isn't really a VM problem, but a bug in my 
patched vmxnet3 driver (which happens with ALTQ usage, ALTQ is the 
reason I can't use if_vmx(4)):

#4  0x00e329fd in vm_fault_hold (map=0x1edc000, vaddr=0, 
fault_type=<value optimized out>, fault_flags=0, m_hold=0x0)
     at /usr/local/share/deploy-tools/RELENG_12/src/sys/vm/vm_fault.c:600
#5  0x00e303fa in vm_fault (map=0x1edc000, vaddr=0, fault_type=1 '\001', 
fault_flags=0)
     at /usr/local/share/deploy-tools/RELENG_12/src/sys/vm/vm_fault.c:550
#6  0x00ea6c6e in trap_pfault (frame=<value optimized out>, usermode=0, 
eva=40)
     at /usr/local/share/deploy-tools/RELENG_12/src/sys/i386/i386/trap.c:884
#7  0x00ea630c in trap (frame=0x471dee8) at 
/usr/local/share/deploy-tools/RELENG_12/src/sys/i386/i386/trap.c:521
#8  0xffc0316d in ?? ()
#9  0x013e663a in vmxnet3_start () from /boot/modules/vmxnet3.ko
#10 0x00c0921a in if_transmit (ifp=0x5241000, m=0x18d7cd00) at 
/usr/local/share/deploy-tools/RELENG_12/src/sys/net/if.c:4048
#11 0x00c0ca82 in ether_output_frame (ifp=0x5241000, m=<value optimized 
out>)
     at 
/usr/local/share/deploy-tools/RELENG_12/src/sys/net/if_ethersubr.c:487
#12 0x00c0c99c in ether_output (ifp=0x5241000, m=<value optimized out>, 
dst=0x471e174, ro=0x471e160)
     at 
/usr/local/share/deploy-tools/RELENG_12/src/sys/net/if_ethersubr.c:440
#13 0x00c5dc6c in ip_output (m=<value optimized out>, opt=0x0, ro=<value 
optimized out>, flags=1, imo=<value optimized out>,
     inp=0x0) at 
/usr/local/share/deploy-tools/RELENG_12/src/sys/netinet/ip_output.c:660
#14 0x00c5a436 in ip_forward (m=0x18d7cd00, srcrt=0) at 
/usr/local/share/deploy-tools/RELENG_12/src/sys/netinet/ip_input.c:1069
#15 0x00c59ce7 in ip_input (m=<value optimized out>) at 
RELENG_12/src/sys/i386/include/counter.h:59
#16 0x00c25f2d in netisr_dispatch_src (proto=1, source=0, m=0x18d7cd00)
     at /usr/local/share/deploy-tools/RELENG_12/src/sys/net/netisr.c:1122
#17 0x00c26230 in netisr_dispatch (proto=1, m=0x18d7cd00) at 
/usr/local/share/deploy-tools/RELENG_12/src/sys/net/netisr.c:1213
#18 0x00c0cbc1 in ether_demux (ifp=0x5230c00, m=<value optimized out>)
     at 
/usr/local/share/deploy-tools/RELENG_12/src/sys/net/if_ethersubr.c:879
#19 0x00c0dc17 in ether_nh_input (m=0x18d7cd00) at 
/usr/local/share/deploy-tools/RELENG_12/src/sys/net/if_ethersubr.c:667
#20 0x00c25f2d in netisr_dispatch_src (proto=5, source=0, m=0x18d7cd00)
     at /usr/local/share/deploy-tools/RELENG_12/src/sys/net/netisr.c:1122