Re: Xen3 domU crashes

On Thu, May 10, 2007 at 08:35:17PM +0300, Martti Kuparinen
wrote:
> Re: Number of interfaces in Xen 3
> 
> So I'm running NetBSD 4.0_BETA2 and I tried to add 16
interfaces to my domU 
> but it crashed. It works with 7 interfaces but more
than 7 caused the domU 
> to crash like this.
> 
> Martti
> 
> 
> xenbus0 at hypervisor0: Xen Virtual Bus Interface
> xencons0 at hypervisor0: Xen Virtual Console Driver
> xencons0: console major 143, unit 0
> xencons0: using event channel 2
> npx0 at hypervisor0: using exception 16
> Xen clock: using event channel 4
> Kernelized RAIDframe activated
> md0: internal 5000 KB image area
> xenbus0: using event channel 1
> [...]
> xennet15 at xenbus0 id 15: Xen Virtual Network
Interface
> xennet15: MAC address 00:16:3e:00:00:10
> xbd0 at xenbus0 id 1: Xen Virtual Block Device
Interface
> uvm_fault(0xc0730140, 0xe0750000, 2) -> 0xe
> kernel: supervisor trap page fault, code=0
> Stopped in pid 3.1 (xenwatch) at        netbsdengnt
_free_entry+0x2b:  orl 
> %
> edx,netbsd:gnt_entries_bitmask(,%ebx,4)
> db>

Hum, I'm not sure I tried that many interfaces on a xen3
system.
Does your kernel have DIAGNOSTIC  (it's in XEN2_DOMU and
XEN3_DOMU by
default, but not INSTALL_XEN*) ?

Looks like we're running out of grant entries. I don't have
an immediate
solution for this; other than maybe hacking
if_xennet_xenbus.c to
use less receive buffer (in xennet_xenbus_attach(), change
the for(;;) loop
to use something less than NET_RX_RING_SIZE - it may work
but I've not
tested it 

Xen 3.0.4 is still limited to 4 grant pages per domain;
-unstable has
a much larger limit but I don't know if it'll be in 3.0.5.

-- 
Manuel Bouyer <bouyerantioche.eu.org>
     NetBSD: 26 ans d'experience feront toujours la
difference
--

Here the normal XEN3_DOMU after installation. I added 8
interfaces to my 
confuration file and it crashed like this. Is there anything
else you'd like to 
know?


xennet7 at xenbus0 id 7: Xen Virtual Network Interface
xennet7: MAC address 00:16:3e:00:00:05
xennet7: using event channel 13
panic: xbdstart: xengnt_grant_access
Stopped in pid 4.1 (xenwatch) at       
netbsd:cpu_Debugger+0x4:        popl    %
ebp
db> bt
cpu_Debugger(c0410c0e,ca93b9e8,7338,58d5c000,c0fb18f4) at
netbsd:cpu_Debugger+0x
4
panic(c0412007,58d5c000,0,c0fb18f4,0) at netbsd:panic+0x155
xbdstart(c0fb103c,ca94df04,ca93ba9c,ca94df04,8) at
netbsdbdsta
rt+0x512
dk_start(c04421d0,c0fb103c,0,c02990a3,0) at
netbsd:dk_start+0x3e
dk_strategy(c04421d0,c0fb103c,ca94df04,c02e7a5c,ca94bd4c) at
netbsd:dk_strategy+
0x13e
xbdstrategy(ca94df04,ca94bd4c,0,c0fc8600,ca93bb9c) at
netbsdbdstr
ategy+0x69
read_sector(0,0,ca93bb1c,c02f865a,0) at
netbsd:read_sector+0x6a
scan_mbr(400,2,ca93bbdc,c02d636c,c0457080) at
netbsd:scan_mbr+0x39
readdisklabel(3,c03a0dd0,c0fc8600,c0fc8400,0) at
netbsd:readdisklabel+0xdc
dk_getdisklabel(c04421d0,c0fb103c,0,c0fb193c,a) at
netbsd:dk_getdisklabel+0xa8
xbd_backend_changed(c0fb1000,4,2,0,0) at netbsdbd_ba
ckend_changed+0x1f5
xenwatch_thread(ca94bd4c,0,c01001e7,c01001df,c01001e7) at
netbsdenwat
ch_thread
+0x94
db>