Linux Guest OS becomes suspended after reading /dev/port
search cancel

Linux Guest OS becomes suspended after reading /dev/port


Article ID: 321909


Updated On:


VMware vSphere ESXi


  • The purpose of this KB is to recommend not to read /dev/port on Linux Guest OS.
  • Linux Guest OS may not become suspended if its datastore is not enough to store snapshot.

  • Linux Guest OS becomes suspended after reading /dev/port such as "cat /dev/port".
  • In the vmware.log, you see entries similar to:

2018-12-17T04:29:51.417Z| vcpu-0| I125: PIIX4: PM Suspending to processor level 3 (C3)...

2018-12-17T04:29:51.463Z| vmx| I125: SUSPEND: Start suspend (flags=0)

2018-12-17T04:29:51.522Z| vcpu-0| I125: Destroying virtual dev for scsi0:0 vscsi=8197

2018-12-17T04:29:51.522Z| vcpu-0| I125: VMMon_VSCSIStopVports: No such target on adapter

2018-12-17T04:29:51.572Z| vcpu-0| I125: Closing all the disks of the VM.

2018-12-17T04:29:51.572Z| vcpu-0| I125: Closing disk 'scsi0:0'

2018-12-17T04:29:51.620Z| vcpu-0| I125: DISKLIB-VMFS  : "/vmfs/volumes/5bf90342-9056c317-29b1-005056b051a0/Web-Tier-ubuntu/Web-Tier-ubuntu-flat.vmdk" : closed.

2018-12-17T04:29:51.865Z| vcpu-0| I125: Progress -1% (msg.checkpoint.saveStatus)

2018-12-17T04:29:51.866Z| vcpu-0| I125: Checkpointed in VMware ESX, 6.7.0, build-10302608, Linux Host

2018-12-17T04:29:51.868Z| vcpu-0| I125: Intel VT: FlexPriority disabled in checkpoint.

2018-12-17T04:29:51.869Z| vcpu-0| I125: Intel VT: FlexPriority disabled in checkpoint.

2018-12-17T04:29:52.348Z| vcpu-0| I125: Progress 0% (none)

2018-12-17T04:29:52.348Z| vcpu-0| I125: MainMem: Writing full memory image, '/vmfs/volumes/5bf90342-9056c317-29b1-005056b051a0/Web-Tier-ubuntu/Web-Tier-ubuntu-6bd22366.vmem'.

2018-12-17T04:30:04.325Z| vcpu-0| I125: Progress 1% (none)

2018-12-17T04:30:09.278Z| vcpu-0| I125: Progress 2% (none)

2018-12-17T04:30:09.679Z| vcpu-0| I125: Progress 3% (none)

2018-12-17T04:30:10.050Z| vcpu-0| I125: Progress 4% (none)

2018-12-17T04:30:10.299Z| vcpu-0| I125: Progress 5% (none)

2018-12-17T04:30:10.706Z| vcpu-0| I125: Progress 6% (none)

2018-12-17T04:30:11.035Z| vcpu-0| I125: Progress 7% (none)

2018-12-17T04:30:11.491Z| vcpu-0| I125: Progress 8% (none)


VMware vSphere ESXi 6.7
VMware vSphere ESXi 5.5
VMware vSphere ESXi 6.0
VMware vSphere ESXi 6.5


  • ESXi emulates PIIX4 and reading its PLVL3 I/O port can cause a guest to suspend.
  • "cat /dev/port" reads from every possible I/O port including PLVL3 in the I/O address space.


  • Recommend not to read /dev/port such as "cat /dev/port".

Additional Information

  • Linux Guest OS becomes suspended.
  • Reading /dev/port can have unknown other side effects and is not safe.