[Qemu-devel] [Bug 1798057] Re: Not able to start instances larger than 1 TB

[Dr. David Alan Gilbert]

Hi Alex,
  You should be able to fix this by passing the right cpu flags, e.g.:

-cpu IvyBridge,host-phys-bits=yes

or

-cpu IvyBridge,physbits=46

Dave

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https://bugs.launchpad.net/bugs/1798057

Title:
  Not able to start instances larger than 1 TB

Status in QEMU:
  New

Bug description:
  Specs:

  CPU: Intel(R) Xeon(R) Gold 6132 CPU @ 2.60GHz
  OS: Ubuntu 18.04 AMD64
  QEMU: 1:2.11+dfsg-1ubuntu7.6 (Ubuntu Bionic Package)
  Openstack: Openstack Queens (Ubuntu Bionic Package)
  Libvirt-daemon: 4.0.0-1ubuntu8.5
  Seabios: 1.10.2-1ubuntu1

  
  The Problem:
  We are not able to start instances, which have a memory size over 1 TB.
  After starting the instance, they shortly lock up. Starting guests with a 
lower amount of RAM works
  perfectly. We dealt with the same problem in the past with an older Qemu 
Version (2.5) by patching some source files according to this patch:

  https://git.centos.org/blob/rpms!!qemu-
  kvm.git/34b32196890e2c41b0aee042e600ba422f29db17/SOURCES!kvm-fix-
  guest-physical-bits-to-match-host-to-go-beyond-1.patch

  
  I think we now have somewhat the same problem here, however the source base 
changed and I'am not able to find the corresponding snippet to patch this.

  Also, guests show a wrong physical address size which is probably the cause 
of the lock ups on high memory guests:
  address@hidden:~# grep physical /proc/cpuinfo 
  physical id   : 0
  address sizes : 40 bits physical, 48 bits virtual 

  Any way to fix this?

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