title: triple-dash on linux kernel command line switches
body: <p>I'm trying to add a switch to send linux kernel log to the serial console on XenServer6.</p>
  
  <p>The kernel command options can be edited on the EXTLinux config file ( <code>/boot/extlinux.conf</code> ).</p>
  
  <p>Here is an excerpt:</p>
  
  <pre><code>serial 1 115200
  default xe
  prompt 1
  timeout 50
  
  label xe
    # XenServer
    kernel mboot.c32
    append /boot/xen.gz mem=1024G dom0_max_vcpus=4 dom0_mem=752M lowmem_emergency_pool=1M crashkernel=64M@32M console= vga=mode-0x0311 --- /boot/vmlinuz-2.6-xen root=LABEL=root-tfnnfzfp ro xencons=hvc com2=115200,8n1 console=com2 console=hvc0 console=tty0 quiet vga=785 splash --- /boot/initrd-2.6-xen.img
  
  label xe-serial
    # XenServer (Serial)
    kernel mboot.c32
    append /boot/xen.gz com1=115200,8n1 console=com1,vga mem=1024G dom0_max_vcpus=4 dom0_mem=752M lowmem_emergency_pool=1M crashkernel=64M@32M --- /boot/vmlinuz-2.6-xen root=LABEL=root-tfnnfzfp ro console=tty0 xencons=hvc console=hvc0 --- /boot/initrd-2.6-xen.img
  </code></pre>
  
  <p>What is the meaning of the triple dashes ( <code>---</code> )on the command line?</p>
  
  <p>Is it loading 3 boot files?</p>