def bootloader(blexec,
disk,
dom,
quiet=False,
blargs='',
kernel='',
ramdisk='',
kernel_args=''):
"""Run the boot loader executable on the given disk and return a
config image.
@param blexec Binary to use as the boot loader
@param disk Disk to run the boot loader on.
@param dom DomainInfo representing the domain being booted.
@param quiet Run in non-interactive mode, just booting the default.
@param blargs Arguments to pass to the bootloader."""
if not os.access(blexec, os.X_OK):
msg = "Bootloader isn't executable"
log.error(msg)
raise VmError(msg)
if not os.access(disk, os.R_OK):
msg = "Disk isn't accessible"
log.error(msg)
raise VmError(msg)
mkdir.parents("/var/run/xend/boot/", stat.S_IRWXU)
while True:
fifo = "/var/run/xend/boot/xenbl.%s" % (random.randint(0, 32000), )
try:
os.mkfifo(fifo, 0600)
except OSError, e:
if (e.errno != errno.EEXIST):
raise
break
def bootloader(blexec,
disk,
dom,
quiet=False,
blargs='',
kernel='',
ramdisk='',
kernel_args=''):
"""Run the boot loader executable on the given disk and return a
config image.
@param blexec Binary to use as the boot loader
@param disk Disk to run the boot loader on.
@param dom DomainInfo representing the domain being booted.
@param quiet Run in non-interactive mode, just booting the default.
@param blargs Arguments to pass to the bootloader."""
if not os.access(blexec, os.X_OK):
msg = "Bootloader isn't executable"
log.error(msg)
raise VmError(msg)
# domUloader requires '--entry=foo' in blargs, which is derived from
# 'bootargs' entry in domain configuration file. Ensure it exists
# here so a reasonable error message can be returned.
if blexec.find('domUloader.py') != -1:
if blargs.find('entry') == -1:
msg = "domUloader requires specification of bootargs"
log.error(msg)
raise VmError(msg)
avail = False
for i in xrange(1, 500):
avail = os.access(disk, os.R_OK)
if avail:
break
time.sleep(.1)
if not avail:
msg = "Disk '%s' isn't accessible" % disk
log.error(msg)
raise VmError(msg)
if os.uname()[0] == "NetBSD" and disk.startswith('/dev/'):
disk = "/r".join(disk.rsplit("/", 1))
mkdir.parents("/var/run/xend/boot/", stat.S_IRWXU)
while True:
fifo = "/var/run/xend/boot/xenbl.%s" % (random.randint(0, 32000), )
try:
os.mkfifo(fifo, 0600)
except OSError, e:
if (e.errno != errno.EEXIST):
raise
break
def get_dom0_target_alloc():
"""Returns the target memory allocation (in KiB) of dom0."""
kb = _get_proc_balloon(labels['target'])
if kb == None:
raise VmError('Failed to query target memory allocation of dom0.')
return kb
def get_dom0_current_alloc():
"""Returns the current memory allocation (in KiB) of dom0."""
kb = _get_proc_balloon('current')
if kb == None:
raise VmError('Failed to query current memory allocation of dom0.')
return kb
def increase_memory(self, value):
if not self.is_enabled():
return
else:
self.reserve_memory += value
if self.reserve_memory > self.default_reserved_memory:
raise VmError(('the maxsize of memory pool is %d KiB, but current is %d KiB') %(value,self.reserve_memory))
log.debug("MemoryPool: increase_memory:%d, reserved_memory %d KiB" %(value,self.reserve_memory))
return
def decrease_untouched_memory(self, value):
if not self.is_enabled():
return
elif self.untouched_memory < value:
raise VmError(('I need %d KiB untouch mem, but only have %d KiB untouched mem in Memory Pool') %(value,self.reserve_memory))
else:
self.untouched_memory -= value
log.debug("MemoryPool: decrease_untouched_memory: untouched_memory %d KiB" %self.untouched_memory)
return
def bootloader(blexec, disk, quiet = 0, vcpus = None, entry = None):
"""Run the boot loader executable on the given disk and return a
config image.
@param blexec Binary to use as the boot loader
@param disk Disk to run the boot loader on.
@param quiet Run in non-interactive mode, just booting the default.
@param vcpus Number of vcpus for the domain.
@param entry Default entry to boot."""
if not os.access(blexec, os.X_OK):
msg = "Bootloader isn't executable"
log.error(msg)
raise VmError(msg)
if not os.access(disk, os.R_OK):
msg = "Disk isn't accessible"
log.error(msg)
raise VmError(msg)
while True:
fifo = "/var/lib/xen/xenbl.%s" %(random.randint(0, 32000),)
if not os.path.exists(fifo):
break
os.mkfifo(fifo, 0600)
child = os.fork()
if (not child):
args = [ blexec ]
if quiet:
args.append("-q")
args.append("--output=%s" %(fifo,))
if entry is not None:
args.append("--entry=%s" %(entry,))
args.append(disk)
try:
os.execvp(args[0], args)
except OSError, e:
print e
pass
os._exit(1)
def free(need_mem):
"""Balloon out memory from the privileged domain so that there is the
specified required amount (in KiB) free.
"""
# We check whether there is enough free memory, and if not, instruct dom0
# to balloon out to free some up. Memory freed by a destroyed domain may
# not appear in the free_memory field immediately, because it needs to be
# scrubbed before it can be released to the free list, which is done
# asynchronously by Xen; ballooning is asynchronous also. Such memory
# does, however, need to be accounted for when calculating how much dom0
# needs to balloon. No matter where we expect the free memory to come
# from, we need to wait for it to become available.
#
# We are not allowed to balloon below dom0_min_mem, or if dom0_min_mem
# is 0, we cannot balloon at all. Memory can still become available
# through a rebooting domain, however.
#
# Eventually, we time out (presumably because there really isn't enough
# free memory).
#
# We don't want to set the memory target (triggering a watch) when that
# has already been done, but we do want to respond to changing memory
# usage, so we recheck the required alloc each time around the loop, but
# track the last used value so that we don't trigger too many watches.
xoptions = XendOptions.instance()
dom0 = XendDomain.instance().privilegedDomain()
xc = xen.lowlevel.xc.xc()
dom0_start_alloc_mb = get_dom0_current_alloc() / 1024
try:
dom0_min_mem = xoptions.get_dom0_min_mem() * 1024
dom0_alloc = get_dom0_current_alloc()
retries = 0
sleep_time = SLEEP_TIME_GROWTH
new_alloc = 0
last_new_alloc = None
last_free = None
rlimit = RETRY_LIMIT
# If unreasonable memory size is required, we give up waiting
# for ballooning or scrubbing, as if had retried.
physinfo = xc.physinfo()
free_mem = physinfo['free_memory']
scrub_mem = physinfo['scrub_memory']
total_mem = physinfo['total_memory']
if dom0_min_mem > 0:
max_free_mem = total_mem - dom0_min_mem
else:
max_free_mem = total_mem - dom0_alloc
if need_mem >= max_free_mem:
retries = rlimit
while retries < rlimit:
physinfo = xc.physinfo()
free_mem = physinfo['free_memory']
scrub_mem = physinfo['scrub_memory']
if free_mem >= need_mem:
log.debug("Balloon: %d KiB free; need %d; done.", free_mem,
need_mem)
return
if retries == 0:
rlimit += (
(need_mem - free_mem) / 1024 / 1024) * RETRY_LIMIT_INCR
log.debug(
"Balloon: %d KiB free; %d to scrub; need %d; retries: %d.",
free_mem, scrub_mem, need_mem, rlimit)
if dom0_min_mem > 0:
dom0_alloc = get_dom0_current_alloc()
new_alloc = dom0_alloc - (need_mem - free_mem - scrub_mem)
if free_mem + scrub_mem >= need_mem:
if last_new_alloc == None:
log.debug("Balloon: waiting on scrubbing")
last_new_alloc = dom0_alloc
else:
if (new_alloc >= dom0_min_mem
and new_alloc != last_new_alloc):
new_alloc_mb = new_alloc / 1024 # Round down
log.debug("Balloon: setting dom0 target to %d MiB.",
new_alloc_mb)
dom0.setMemoryTarget(new_alloc_mb)
last_new_alloc = new_alloc
# Continue to retry, waiting for ballooning or scrubbing.
time.sleep(sleep_time)
if retries < 2 * RETRY_LIMIT:
sleep_time += SLEEP_TIME_GROWTH
if last_free != None and last_free >= free_mem + scrub_mem:
retries += 1
last_free = free_mem + scrub_mem
# Not enough memory; diagnose the problem.
if dom0_min_mem == 0:
raise VmError(('Not enough free memory and dom0_min_mem is 0, so '
'I cannot release any more. I need %d KiB but '
'only have %d.') % (need_mem, free_mem))
elif new_alloc < dom0_min_mem:
raise VmError(
('I need %d KiB, but dom0_min_mem is %d and shrinking to '
'%d KiB would leave only %d KiB free.') %
(need_mem, dom0_min_mem, dom0_min_mem,
free_mem + scrub_mem + dom0_alloc - dom0_min_mem))
else:
dom0.setMemoryTarget(dom0_start_alloc_mb)
raise VmError(('Not enough memory is available, and dom0 cannot'
' be shrunk any further'))
finally:
del xc
def free(need_mem, dominfo):
"""Balloon out memory from the privileged domain so that there is the
specified required amount (in KiB) free.
"""
# We check whether there is enough free memory, and if not, instruct dom0
# to balloon out to free some up. Memory freed by a destroyed domain may
# not appear in the free_memory field immediately, because it needs to be
# scrubbed before it can be released to the free list, which is done
# asynchronously by Xen; ballooning is asynchronous also. Such memory
# does, however, need to be accounted for when calculating how much dom0
# needs to balloon. No matter where we expect the free memory to come
# from, we need to wait for it to become available.
#
# We are not allowed to balloon below dom0_min_mem, or if dom0_ballooning
# is False, we cannot balloon at all. Memory can still become available
# through a rebooting domain, however.
#
# Eventually, we time out (presumably because there really isn't enough
# free memory).
#
# We don't want to set the memory target (triggering a watch) when that
# has already been done, but we do want to respond to changing memory
# usage, so we recheck the required alloc each time around the loop, but
# track the last used value so that we don't trigger too many watches.
xoptions = XendOptions.instance()
dom0 = XendDomain.instance().privilegedDomain()
xc = xen.lowlevel.xc.xc()
memory_pool = MemoryPool.instance()
try:
dom0_min_mem = xoptions.get_dom0_min_mem() * 1024
dom0_ballooning = xoptions.get_enable_dom0_ballooning()
guest_size = 0
hvm = dominfo.info.is_hvm()
if memory_pool.is_enabled() and dominfo.domid:
if not hvm:
if need_mem <= 4 * 1024:
guest_size = 32
else:
guest_size = dominfo.image.getBitSize()
if guest_size == 32:
dom0_ballooning = 0
else: #no ballooning as memory pool enabled
dom0_ballooning = xoptions.get_enable_dom0_ballooning()
dom0_alloc = get_dom0_current_alloc()
retries = 0
sleep_time = SLEEP_TIME_GROWTH
new_alloc = 0
last_new_alloc = None
last_free = None
rlimit = RETRY_LIMIT
mem_need_balloon = 0
left_memory_pool = 0
mem_target = 0
untouched_memory_pool = 0
real_need_mem = need_mem
# stop tmem from absorbing any more memory (must THAW when done!)
xc.tmem_control(0, TMEMC_FREEZE, -1, 0, 0, 0, "")
# If unreasonable memory size is required, we give up waiting
# for ballooning or scrubbing, as if had retried.
physinfo = xc.physinfo()
free_mem = physinfo['free_memory']
scrub_mem = physinfo['scrub_memory']
total_mem = physinfo['total_memory']
if memory_pool.is_enabled() and dominfo.domid:
if guest_size != 32 or hvm:
if need_mem > 4 * 1024:
dominfo.alloc_mem = need_mem
left_memory_pool = memory_pool.get_left_memory()
if need_mem > left_memory_pool:
dominfo.alloc_mem = 0
raise VmError(
('Not enough free memory'
' so I cannot release any more. '
'I need %d KiB but only have %d in the pool.') %
(need_mem, memory_pool.get_left_memory()))
else:
untouched_memory_pool = memory_pool.get_untouched_memory()
if (left_memory_pool - untouched_memory_pool) > need_mem:
dom0_ballooning = 0
else:
mem_need_balloon = need_mem - left_memory_pool + untouched_memory_pool
need_mem = free_mem + scrub_mem + mem_need_balloon
if dom0_ballooning:
max_free_mem = total_mem - dom0_min_mem
else:
max_free_mem = total_mem - dom0_alloc
if need_mem >= max_free_mem:
retries = rlimit
freeable_mem = free_mem + scrub_mem
if freeable_mem < need_mem and need_mem < max_free_mem:
# flush memory from tmem to scrub_mem and reobtain physinfo
need_tmem_kb = need_mem - freeable_mem
tmem_kb = xc.tmem_control(0, TMEMC_FLUSH, -1, need_tmem_kb, 0, 0,
"")
log.debug("Balloon: tmem relinquished %d KiB of %d KiB requested.",
tmem_kb, need_tmem_kb)
physinfo = xc.physinfo()
free_mem = physinfo['free_memory']
scrub_mem = physinfo['scrub_memory']
while retries < rlimit:
physinfo = xc.physinfo()
free_mem = physinfo['free_memory']
scrub_mem = physinfo['scrub_memory']
if free_mem >= need_mem:
if (guest_size != 32 or hvm) and dominfo.domid:
memory_pool.decrease_untouched_memory(mem_need_balloon)
memory_pool.decrease_memory(real_need_mem)
else:
log.debug("Balloon: %d KiB free; need %d; done.", free_mem,
need_mem)
return
if retries == 0:
rlimit += (
(need_mem - free_mem) / 1024 / 1024) * RETRY_LIMIT_INCR
log.debug(
"Balloon: %d KiB free; %d to scrub; need %d; retries: %d.",
free_mem, scrub_mem, need_mem, rlimit)
if dom0_ballooning:
dom0_alloc = get_dom0_current_alloc()
new_alloc = dom0_alloc - (need_mem - free_mem - scrub_mem)
if free_mem + scrub_mem >= need_mem:
if last_new_alloc == None:
log.debug("Balloon: waiting on scrubbing")
last_new_alloc = dom0_alloc
else:
if (new_alloc >= dom0_min_mem
and new_alloc != last_new_alloc):
new_alloc_mb = new_alloc / 1024 # Round down
log.debug("Balloon: setting dom0 target to %d MiB.",
new_alloc_mb)
dom0.setMemoryTarget(new_alloc_mb)
last_new_alloc = new_alloc
# Continue to retry, waiting for ballooning or scrubbing.
time.sleep(sleep_time)
if retries < 2 * RETRY_LIMIT:
sleep_time += SLEEP_TIME_GROWTH
if last_free != None and last_free >= free_mem + scrub_mem:
retries += 1
last_free = free_mem + scrub_mem
# Not enough memory; diagnose the problem.
if not dom0_ballooning:
dominfo.alloc_mem = 0
raise VmError(
('Not enough free memory and enable-dom0-ballooning '
'is False, so I cannot release any more. '
'I need %d KiB but only have %d.') % (need_mem, free_mem))
elif new_alloc < dom0_min_mem:
dominfo.alloc_mem = 0
raise VmError(
('I need %d KiB, but dom0_min_mem is %d and shrinking to '
'%d KiB would leave only %d KiB free.') %
(need_mem, dom0_min_mem, dom0_min_mem,
free_mem + scrub_mem + dom0_alloc - dom0_min_mem))
else:
dom0_start_alloc_mb = get_dom0_current_alloc() / 1024
dom0.setMemoryTarget(dom0_start_alloc_mb)
dominfo.alloc_mem = 0
raise VmError(('Not enough memory is available, and dom0 cannot'
' be shrunk any further'))
finally:
# allow tmem to accept pages again
xc.tmem_control(0, TMEMC_THAW, -1, 0, 0, 0, "")
del xc
def free(required):
"""Balloon out memory from the privileged domain so that there is the
specified required amount (in KiB) free.
"""
# We check whether there is enough free memory, and if not, instruct dom0
# to balloon out to free some up. Memory freed by a destroyed domain may
# not appear in the free_memory field immediately, because it needs to be
# scrubbed before it can be released to the free list, which is done
# asynchronously by Xen; ballooning is asynchronous also. No matter where
# we expect the free memory to come from, therefore, we need to wait for
# it to become available.
#
# We are not allowed to balloon below dom0_min_mem, or if dom0_min_mem
# is 0, we cannot balloon at all. Memory can still become available
# through a rebooting domain, however.
#
# Eventually, we time out (presumably because there really isn't enough
# free memory).
#
# We don't want to set the memory target (triggering a watch) when that
# has already been done, but we do want to respond to changing memory
# usage, so we recheck the required alloc each time around the loop, but
# track the last used value so that we don't trigger too many watches.
need_mem = (required + 1023) / 1024 + BALLOON_OUT_SLACK
xroot = XendRoot.instance()
xc = xen.lowlevel.xc.xc()
try:
dom0_min_mem = xroot.get_dom0_min_mem()
retries = 0
sleep_time = SLEEP_TIME_GROWTH
last_new_alloc = None
while retries < RETRY_LIMIT:
free_mem = xc.physinfo()['free_memory']
if free_mem >= need_mem:
log.debug("Balloon: free %d; need %d; done.", free_mem,
need_mem)
return
if retries == 0:
log.debug("Balloon: free %d; need %d.", free_mem, need_mem)
if dom0_min_mem > 0:
dom0_alloc = get_dom0_current_alloc()
new_alloc = dom0_alloc - (need_mem - free_mem)
if (new_alloc >= dom0_min_mem and new_alloc != last_new_alloc):
log.debug("Balloon: setting dom0 target to %d.", new_alloc)
dom0 = XendDomain.instance().privilegedDomain()
dom0.setMemoryTarget(new_alloc)
last_new_alloc = new_alloc
# Continue to retry, waiting for ballooning.
time.sleep(sleep_time)
retries += 1
sleep_time += SLEEP_TIME_GROWTH
# Not enough memory; diagnose the problem.
if dom0_min_mem == 0:
raise VmError(('Not enough free memory and dom0_min_mem is 0, so '
'I cannot release any more. I need %d MiB but '
'only have %d.') % (need_mem, free_mem))
elif new_alloc < dom0_min_mem:
raise VmError(
('I need %d MiB, but dom0_min_mem is %d and shrinking to '
'%d MiB would leave only %d MiB free.') %
(need_mem, dom0_min_mem, dom0_min_mem,
free_mem + dom0_alloc - dom0_min_mem))
else:
raise VmError('The privileged domain did not balloon!')
finally:
del xc
def free(need_mem, dominfo):
"""Balloon out memory from the privileged domain so that there is the
specified required amount (in KiB) free.
"""
# We check whether there is enough free memory, and if not, instruct dom0
# to balloon out to free some up. Memory freed by a destroyed domain may
# not appear in the free_memory field immediately, because it needs to be
# scrubbed before it can be released to the free list, which is done
# asynchronously by Xen; ballooning is asynchronous also. Such memory
# does, however, need to be accounted for when calculating how much dom0
# needs to balloon. No matter where we expect the free memory to come
# from, we need to wait for it to become available.
#
# We are not allowed to balloon below dom0_min_mem, or if dom0_ballooning
# is False, we cannot balloon at all. Memory can still become available
# through a rebooting domain, however.
#
# Eventually, we time out (presumably because there really isn't enough
# free memory).
#
# We don't want to set the memory target (triggering a watch) when that
# has already been done, but we do want to respond to changing memory
# usage, so we recheck the required alloc each time around the loop, but
# track the last used value so that we don't trigger too many watches.
xoptions = XendOptions.instance()
dom0 = XendDomain.instance().privilegedDomain()
xc = xen.lowlevel.xc.xc()
try:
dom0_min_mem = xoptions.get_dom0_min_mem() * 1024
dom0_ballooning = xoptions.get_enable_dom0_ballooning()
dom0_alloc = get_dom0_current_alloc()
retries = 0
sleep_time = SLEEP_TIME_GROWTH
new_alloc = 0
last_new_alloc = None
last_free = None
rlimit = RETRY_LIMIT
# stop tmem from absorbing any more memory (must THAW when done!)
xc.tmem_control(0,TMEMC_FREEZE,-1, 0, 0, "")
# If unreasonable memory size is required, we give up waiting
# for ballooning or scrubbing, as if had retried.
physinfo = xc.physinfo()
free_mem = physinfo['free_memory']
scrub_mem = physinfo['scrub_memory']
total_mem = physinfo['total_memory']
if dom0_ballooning:
max_free_mem = total_mem - dom0_min_mem
else:
max_free_mem = total_mem - dom0_alloc
if need_mem >= max_free_mem:
retries = rlimit
freeable_mem = free_mem + scrub_mem
if freeable_mem < need_mem and need_mem < max_free_mem:
# flush memory from tmem to scrub_mem and reobtain physinfo
need_tmem_kb = need_mem - freeable_mem
tmem_kb = xc.tmem_control(0,TMEMC_FLUSH,-1, need_tmem_kb, 0, "")
log.debug("Balloon: tmem relinquished %d KiB of %d KiB requested.",
tmem_kb, need_tmem_kb)
physinfo = xc.physinfo()
free_mem = physinfo['free_memory']
scrub_mem = physinfo['scrub_memory']
# Check whethercurrent machine is a numa system and the new
# created hvm has all its vcpus in the same node, if all the
# conditions above are fit. We will wait until all the pages
# in scrub list are freed (if waiting time go beyond 20s,
# we will stop waiting it.)
if physinfo['nr_nodes'] > 1 and retries == 0:
oldnode = -1
waitscrub = 1
vcpus = dominfo.info['cpus'][0]
for vcpu in vcpus:
nodenum = 0
for node in physinfo['node_to_cpu']:
for cpu in node:
if vcpu == cpu:
if oldnode == -1:
oldnode = nodenum
elif oldnode != nodenum:
waitscrub = 0
nodenum = nodenum + 1
if waitscrub == 1 and scrub_mem > 0:
log.debug("wait for scrub %s", scrub_mem)
while scrub_mem > 0 and retries < rlimit:
time.sleep(sleep_time)
physinfo = xc.physinfo()
free_mem = physinfo['free_memory']
scrub_mem = physinfo['scrub_memory']
retries += 1
sleep_time += SLEEP_TIME_GROWTH
log.debug("scrub for %d times", retries)
retries = 0
sleep_time = SLEEP_TIME_GROWTH
while retries < rlimit:
physinfo = xc.physinfo()
free_mem = physinfo['free_memory']
scrub_mem = physinfo['scrub_memory']
if free_mem >= need_mem:
log.debug("Balloon: %d KiB free; need %d; done.",
free_mem, need_mem)
return
if retries == 0:
rlimit += ((need_mem - free_mem)/1024/1024) * RETRY_LIMIT_INCR
log.debug("Balloon: %d KiB free; %d to scrub; need %d; retries: %d.",
free_mem, scrub_mem, need_mem, rlimit)
if dom0_ballooning:
dom0_alloc = get_dom0_current_alloc()
new_alloc = dom0_alloc - (need_mem - free_mem - scrub_mem)
if free_mem + scrub_mem >= need_mem:
if last_new_alloc == None:
log.debug("Balloon: waiting on scrubbing")
last_new_alloc = dom0_alloc
else:
if (new_alloc >= dom0_min_mem and
new_alloc != last_new_alloc):
new_alloc_mb = new_alloc / 1024 # Round down
log.debug("Balloon: setting dom0 target to %d MiB.",
new_alloc_mb)
dom0.setMemoryTarget(new_alloc_mb)
last_new_alloc = new_alloc
# Continue to retry, waiting for ballooning or scrubbing.
time.sleep(sleep_time)
if retries < 2 * RETRY_LIMIT:
sleep_time += SLEEP_TIME_GROWTH
if last_free != None and last_free >= free_mem + scrub_mem:
retries += 1
last_free = free_mem + scrub_mem
# Not enough memory; diagnose the problem.
if not dom0_ballooning:
raise VmError(('Not enough free memory and enable-dom0-ballooning '
'is False, so I cannot release any more. '
'I need %d KiB but only have %d.') %
(need_mem, free_mem))
elif new_alloc < dom0_min_mem:
raise VmError(
('I need %d KiB, but dom0_min_mem is %d and shrinking to '
'%d KiB would leave only %d KiB free.') %
(need_mem, dom0_min_mem, dom0_min_mem,
free_mem + scrub_mem + dom0_alloc - dom0_min_mem))
else:
dom0_start_alloc_mb = get_dom0_current_alloc() / 1024
dom0.setMemoryTarget(dom0_start_alloc_mb)
raise VmError(
('Not enough memory is available, and dom0 cannot'
' be shrunk any further'))
finally:
# allow tmem to accept pages again
xc.tmem_control(0,TMEMC_THAW,-1, 0, 0, "")
del xc