Month: May 2020

Categories
OSX

Resizing an OSX VM with apfs and QEMU

Looking to resize an existing qcow2 or raw data volume with QEMU?

I had to do the same thing and went through some trouble in trying to do this. My first idea was to use GParted and boot from the live-cd iso to extend the apfs partition. However, it turns out that GParted does not support apfs (yet?).

First, you’ll need to expand the disk space available to the VM. Depending on the disk format, you can use:

  • qcow2: qemu-img resize image.qcow2 +20G
  • lvm: lvextend -L /dev/lvmpool/vm +20G

Now you can expand the apfs container from inside the OSX VM. Simply find out the identifier of your partition:

/usr/sbin/diskutil info / | awk '/Part of Whole/ {print $4}'

And use that identifier together with this command:

/usr/sbin/diskutil apfs resizeContainer /dev/{identifier} 0

This will expand to use up all available free disk space.

Categories
QEMU

Hyper-V Enlightenments with Libvirt

With Windows 10, it’s helpful to enable Hyper-V Enlightenments, to save CPU and increase VM responsiveness.

To use these enlightenments, edit your libvirt xml:

<features>
  <acpi/>
  <apic/>
  <pae/>
  <hyperv>
    <relaxed state='on'/>
    <vapic state='on'/>
    <spinlocks state='on' retries='8191'/>
    <vpindex state='on'/>
    <synic state='on'/>
    <stimer state='on'/>
    <reset state='on'/>
  </hyperv>
</features>

More information available on https://fossies.org/linux/qemu/docs/hyperv.txt

Another interesting note: if you want to run Windows 10 or similar in a VM, you might want to use these clock timer settings, to avoid high load even when your VM is idle:

<clock offset='localtime'>
  <timer name='rtc' tickpolicy='catchup'/>
  <timer name='pit' tickpolicy='delay'/>
  <timer name='hpet' present='no'/>
  <timer name='hypervclock' present='yes'/>
</clock>
Categories
OSX

Content Caching on OSX VMs

Apple’s Content Caching is not available when running OSX in a VM.

It seems Apple is detecting if it’s running inside a VM:

$ sudo /usr/bin/AssetCacheManagerUtil activate
AssetCacheManagerUtil[] Failed to activate content caching: Error Domain=ACSMErrorDomain Code=5 "virtual machine"...

To get around this, you can patch the kernel to remove the cpuid features check:

  • First disable SIP
  • Next: sudo mount -uw /
  • kernel_autopatcher.py /System/Library/Kernels/kernel
  • sudo kextcache -i /

Reference: https://github.com/kholia/OSX-KVM/blob/master/reversing-notes.md