Re: Instability issues with NetBSD-9, xen-4.11 and the xbdb backend driver

[Brian Buhrow <buhrow%nfbcal.org@localhost>]

	hello.  I think I'm making progress.  The problem seems to be an error
with the shared memory mapping on the back end with dom0.  With backend
debugging turned on, I see the errors below.  

It looks like xen_shm_map() is supposed to return ENOMEM  if it can't
allocate a segment of memory in the moment, but instead, it's returning -1,
which triggers the messages I'm seeing.  At this point, I'm not sure where
the -1 is coming from.  If I'm reading the xen_shm_map function correctly,
if it gets an error it doesn't map to ENOMEM, it's supposed to panic.  yet,
it's not panicing.
	Since I'm using modules to load zfs, it's not a trivial test to switch
kernels to -current.

-thanks
-Brian

Nov 13 12:56:59 xen- /netbsd: [ 817.5700780] xbdback_io domain 2: start sect 67122232 size 8
Nov 13 12:56:59 xen- /netbsd: [ 817.5700780] xbdback op 0 req_cons 0x13589 req_prod 0x13591 resp_prod 0x13589 id 15
Nov 13 12:56:59 xen- /netbsd: [ 817.5700780] xbdback_io domain 2: hoping for sector 67122240; got 42671168
Nov 13 12:56:59 xen- /netbsd: [ 817.5700780] xbdback_io domain 2: segment break
Nov 13 12:56:59 xen- /netbsd: [ 817.5700780] xbdback_io domain 2: flush sect 67122208 size 16384 ptr 0xffffd98010ded038
Nov 13 12:56:59 xen- /netbsd: [ 817.5700780] xbdback_map_shm map grant 400 401 445 403 xbdback_map_shm: xen_shm error -1 xbdback_io domain 2: iodone ptr 0xffffd98010ded038
Nov 13 12:56:59 xen- /netbsd: [ 817.5700780] xbd IO domain 2: error -1
Nov 13 12:56:59 xen- /netbsd: [ 817.5700780] xbdback_io domain 2: end request 5 error=-1
Nov 13 12:56:59 xen- /netbsd: [ 817.5700780] xbdback_send_reply notify 2