RE: XEN 4.0 + 2.6.31.13 pvops kernel : system crashes on starting 155th domU

["Yuvraj Agarwal" <yuvraj@cs.ucsd.edu>]

I am not using grub2; using grub-legacy instead. 

Also, once the dom0 boots up I do have to set the dom0 mem to:

(1) xm mem-set 0 12000   (otherwise when starting up a lot of domU it
would run out of memory) 
and 
(2) echo 1548576 > /proc/sys/fs/aio-max-nr 


My /boot/grub/menu.lst  (pasted relevant lines) 
**************************************************

root@MESL-BlackBox:/usr/src# cat /boot/grub/menu.lst                 
# menu.lst - See: grub(8), info grub, update-grub(8)
#            grub-install(8), grub-floppy(8),
#            grub-md5-crypt, /usr/share/doc/grub
#            and /usr/share/doc/grub-doc/.

## default num
# Set the default entry to the entry number NUM. Numbering starts from 0,
and
# the entry number 0 is the default if the command is not used.
#
# You can specify 'saved' instead of a number. In this case, the default
entry
# is the entry saved with the command 'savedefault'.
# WARNING: If you are using dmraid do not use 'savedefault' or your
# array will desync and will not let you boot your system.
default         0

## timeout sec
# Set a timeout, in SEC seconds, before automatically booting the default
entry
# (normally the first entry defined).
timeout         20

### BEGIN AUTOMAGIC KERNELS LIST
## lines between the AUTOMAGIC KERNELS LIST markers will be modified
## by the debian update-grub script except for the default options below

## DO NOT UNCOMMENT THEM, Just edit them to your needs

## ## Start Default Options ##
## default kernel options
## default kernel options for automagic boot options
## If you want special options for specific kernels use kopt_x_y_z
## where x.y.z is kernel version. Minor versions can be omitted.
## e.g. kopt=root=/dev/hda1 ro
##      kopt_2_6_8=root=/dev/hdc1 ro
##      kopt_2_6_8_2_686=root=/dev/hdc2 ro
# kopt=root=UUID=909f7c32-639a-469d-b34b-b418d2b6a2dc ro

## default grub root device
## e.g. groot=(hd0,0)
# groot=909f7c32-639a-469d-b34b-b418d2b6a2dc

## should update-grub create alternative automagic boot options
## e.g. alternative=true
##      alternative=false
# alternative=true

## should update-grub lock alternative automagic boot options
## e.g. lockalternative=true
##      lockalternative=false
# lockalternative=false

## additional options to use with the default boot option, but not with
the
## alternatives
## e.g. defoptions=vga=791 resume=/dev/hda5
# defoptions=quiet splash

## should update-grub lock old automagic boot options
## e.g. lockold=false
##      lockold=true
# lockold=false

## Xen hypervisor options to use with the default Xen boot option
# xenhopt=dom0_max_vcpus=1 dom0_mem=8192

## Xen Linux kernel options to use with the default Xen boot option
# xenkopt=console=tty0

## altoption boot targets option
## multiple altoptions lines are allowed
## e.g. altoptions=(extra menu suffix) extra boot options
##      altoptions=(recovery) single
# altoptions=(recovery mode) single

## controls how many kernels should be put into the menu.lst
## only counts the first occurence of a kernel, not the
## alternative kernel options
## e.g. howmany=all
##      howmany=7
# howmany=all

## specify if running in Xen domU or have grub detect automatically
## update-grub will ignore non-xen kernels when running in domU and vice
versa
## e.g. indomU=detect
##      indomU=true
##      indomU=false
# indomU=detect

## should update-grub create memtest86 boot option
## e.g. memtest86=true
##      memtest86=false
# memtest86=true

## should update-grub adjust the value of the default booted system
## can be true or false
# updatedefaultentry=false

## should update-grub add savedefault to the default options
## can be true or false
# savedefault=false

## ## End Default Options ##

title           Xen 4.0.0 / Debian GNU/Linux, kernel 2.6.31.13
root            (hd0,0)
kernel          /boot/xen-4.0.0.gz 
module          /boot/vmlinuz-2.6.31.13 root=/dev/sda1 ro 

title           Xen 3.4.2 / Debian GNU/Linux, kernel 2.6.31.8-xenapr2010
root            (hd0,0)
kernel          /boot/xen-3.4.2.gz 
module          /boot/vmlinuz-2.6.31.8-xenapr2010 root=/dev/sda1 ro
console=tty0 
module          /boot/initrd.img-2.6.31.8-xenapr2010

### END DEBIAN AUTOMAGIC KERNELS LIST


Please paste your dom0 grub.conf.
Are you using memory ballooning? 

-- Pasi