OSError: [Errno 10] No child processes

[Noah Cantor <noah.cantor@ims-evolve.com>]

I'm running RHEL 4 with a Xen package compiled from source. Everything 
boots into the xen kernel properly.
I followed the Xen User Guide for configuration options and installed 
Xen into a flat file.
Now, when booting the system, I regularly get this error:



[root@ims-devhost-1 ~]# xm create -c ims-mp7i vmid=2
Using config file "/etc/xen/ims-mp7i".
Started domain VM2
Unexpected error: exceptions.OSError

Please report to xen-devel@lists.xensource.com
Traceback (most recent call last):
  File "/usr/sbin/xm", line 10, in ?
    main.main(sys.argv)
  File "//usr/lib64/python/xen/xm/main.py", line 2453, in main
    _, rc = _run_cmd(cmd, cmd_name, args)
  File "//usr/lib64/python/xen/xm/main.py", line 2477, in _run_cmd
    return True, cmd(args)
  File "<string>", line 1, in <lambda>
  File "//usr/lib64/python/xen/xm/main.py", line 1266, in xm_importcommand
    cmd.main([command] + args)
  File "//usr/lib64/python/xen/xm/create.py", line 1292, in main
    do_console(sxp.child_value(config, 'name', -1))
  File "//usr/lib64/python/xen/xm/create.py", line 1317, in do_console
    (p, rv) = os.waitpid(cpid, os.WNOHANG)
OSError: [Errno 10] No child processes
[root@ims-devhost-1 ~]#




In addition, when this error doesn't occur, the system won't boot anyway.


Here is my configuration file:


[root@ims-devhost-1 ~]# !cat
cat /etc/xen/ims-mp7i
#  -*- mode: python; -*-
#============================================================================
# Example Python setup script for 'xm create'.
# This script sets the parameters used when a domain is created using 
'xm create'.
#
# This is a relatively advanced script that uses a parameter, vmid, to 
control
# the settings. So this script can be used to start a set of domains by
# setting the vmid parameter on the 'xm create' command line. For example:
#
# xm create vmid=1
# xm create vmid=2
# xm create vmid=3
#
# The vmid is purely a script variable, and has no effect on the the domain
# id assigned to the new domain.
#============================================================================

# Define script variables here.
# xm_vars is defined automatically, use xm_vars.var() to define a variable.

# This function checks that 'vmid' has been given a valid value.
# It is called automatically by 'xm create'.
def vmid_check(var, val):
    val = int(val)
    if val <= 0:
        raise ValueError
    return val

# Define the 'vmid' variable so that 'xm create' knows about it.
xm_vars.var('vmid',
            use="Virtual machine id. Integer greater than 0.",
            check=vmid_check)

# Check the defined variables have valid values..
xm_vars.check()

#----------------------------------------------------------------------------
# Kernel image file.
kernel = "/boot/vmlinuz-2.6.9-55.ELxenU"

# Optional ramdisk.
#ramdisk = "/boot/initrd.gz"

# The domain build function. Default is 'linux'.
#builder='linux'

# Initial memory allocation (in megabytes) for the new domain.
#
# WARNING: Creating a domain with insufficient memory may cause out of
#          memory errors. The domain needs enough memory to boot kernel
#          and modules. Allocating less than 32MBs is not recommended.
memory = 1024

# A name for the new domain. All domains have to have different names,
# so we use the vmid to create a name.
name = "VM%d" % vmid

# 128-bit UUID for the domain.  The default behavior is to generate a 
new UUID
# on each call to 'xm create'.
#uuid = "06ed00fe-1162-4fc4-b5d8-11993ee4a8b9"

# List of which CPUS this domain is allowed to use, default Xen picks
#cpus = ""         # leave to Xen to pick
#cpus = "0"        # all vcpus run on CPU0
#cpus = "0-3,5,^1" # run on cpus 0,2,3,5
#cpus = "%s" % vmid # set based on vmid (mod number of CPUs)

# Number of Virtual CPUS to use, default is 1
#vcpus = 1
vcpus = 4 # make your domain a 4-way

#----------------------------------------------------------------------------
# Define network interfaces.

# By default, no network interfaces are configured.  You may have one 
created
# with sensible defaults using an empty vif clause:
#
#vif = [ '' ]
#
# or optionally override backend, bridge, ip, mac, script, type, or vifname:
#
# vif = [ 'mac=00:16:3e:00:00:11, bridge=xenbr0' ]
#vif = [ 'mac=00:16:3e:00:00:11, bridge=bond0' ]
#
# or more than one interface may be configured:
#
# vif = [ '', 'bridge=xenbr1' ]

#vif = [ '' ]

#----------------------------------------------------------------------------
# Define the disk devices you want the domain to have access to, and
# what you want them accessible as.
# Each disk entry is of the form phy:UNAME,DEV,MODE
# where UNAME is the device, DEV is the device name the domain will see,
# and MODE is r for read-only, w for read-write.

# This makes the disk device depend on the vmid - assuming
# that devices sda7, sda8 etc. exist. The device is exported
# to all domains as sda1.
# All domains get sda6 read-only (to use for /usr, see below).
#disk = ['tap:aio:/home/Virts/ims-mp7i,sda1,w']
disk = ['tap:aio:/home/Virts/ims-mp7i,xvda1,w']

#----------------------------------------------------------------------------
# Define frame buffer device.
#
# By default, no frame buffer device is configured.
#
# To create one using the SDL backend and sensible defaults:
#
# vfb = [ 'type=sdl' ]
#
# This uses environment variables XAUTHORITY and DISPLAY.  You
# can override that:
#
# vfb = [ 'type=sdl,xauthority=/home/bozo/.Xauthority,display=:1' ]
#
# To create one using the VNC backend and sensible defaults:
#
# vfb = [ 'type=vnc' ]
#
# The backend listens on 127.0.0.1 port 5900+N by default, where N is
# the domain ID.  You can override both address and N:
#
# vfb = [ 'type=vnc,vnclisten=127.0.0.1,vncdisplay=%d' % vmid ]
#
# Or you can bind the first unused port above 5900:
#
# vfb = [ 'type=vnc,vnclisten=0.0.0.0,vnunused=1' ]
#
# You can override the password:
#
# vfb = [ 'type=vnc,vncpasswd=MYPASSWD' ]
#
# Empty password disables authentication.  Defaults to the vncpasswd
# configured in xend-config.sxp.

#----------------------------------------------------------------------------
# Define to which TPM instance the user domain should communicate.
# The vtpm entry is of the form 'instance=INSTANCE,backend=DOM'
# where INSTANCE indicates the instance number of the TPM the VM
# should be talking to and DOM provides the domain where the backend
# is located.
# Note that no two virtual machines should try to connect to the same
# TPM instance. The handling of all TPM instances does require
# some management effort in so far that VM configration files (and thus
# a VM) should be associated with a TPM instance throughout the lifetime
# of the VM / VM configuration file. The instance number must be
# greater or equal to 1.
#vtpm = ['instance=%d,backend=0' % (vmid) ]

#----------------------------------------------------------------------------
# Set the kernel command line for the new domain.
# You only need to define the IP parameters and hostname if the domain's
# IP config doesn't, e.g. in ifcfg-eth0 or via DHCP.
# You can use 'extra' to set the runlevel and custom environment
# variables used by custom rc scripts (e.g. VMID=, usr= ).

# Set if you want dhcp to allocate the IP address.
#dhcp="dhcp"
# Set netmask.
#netmask=
# Set default gateway.
#gateway=
# Set the hostname.
#hostname= "vm%d" % vmid

# Set root device.
#root = "/dev/sda1 ro"
root = "/dev/xvda1 ro"

# Root device for nfs.
#root = "/dev/nfs"
# The nfs server.
#nfs_server = '169.254.1.0'
# Root directory on the nfs server.
#nfs_root   = '/full/path/to/root/directory'

# Sets runlevel 4 and the device for /usr.
#extra = "4 VMID=%d usr=/dev/sda6" % vmid
extra = "4 VMID=%d " % vmid

#----------------------------------------------------------------------------
# Configure the behaviour when a domain exits.  There are three 'reasons'
# for a domain to stop: poweroff, reboot, and crash.  For each of these you
# may specify:
#
#   "destroy",        meaning that the domain is cleaned up as normal;
#   "restart",        meaning that a new domain is started in place of 
the old
#                     one;
#   "preserve",       meaning that no clean-up is done until the domain is
#                     manually destroyed (using xm destroy, for example); or
#   "rename-restart", meaning that the old domain is not cleaned up, but is
#                     renamed and a new domain started in its place.
#
# The default is
#
#   on_poweroff = 'destroy'
#   on_reboot   = 'restart'
#   on_crash    = 'restart'
#
# For backwards compatibility we also support the deprecated option restart
#
# restart = 'onreboot' means on_poweroff = 'destroy'
#                            on_reboot   = 'restart'
#                            on_crash    = 'destroy'
#
# restart = 'always'   means on_poweroff = 'restart'
#                            on_reboot   = 'restart'
#                            on_crash    = 'restart'
#
# restart = 'never'    means on_poweroff = 'destroy'
#                            on_reboot   = 'destroy'
#                            on_crash    = 'destroy'

#on_poweroff = 'destroy'
#on_reboot   = 'restart'
#on_crash    = 'restart'

#============================================================================
[root@ims-devhost-1 ~]#