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Not able to start instances larger than 1 TB
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:
root@debug:~# grep physical /proc/cpuinfo
physical id : 0
address sizes : 40 bits physical, 48 bits virtual
Any way to fix this?
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
I'm assuming that the right physbits setting fixed the bug? ... so I'm marking this ticket as "Invalid". If the problem still persists, then please open again.
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