After Kernel Update to 4.1.6_1, Can't Boot Virtualbox Guests if Host I/O Cache Disabled

[Antonio Malcolm <antonio...@gmail.com>]

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After updating to kernel 4.1.6_1, I can no longer boot Virtualbox guests if 
"Use Host I/O Cache" is disabled.
It doesn't appear to matter what the guest is. I have several Void guests 
for development, and one Windows 7 guest for testing.
All of them are using SATA with AHCI mode as the storage interface. 

The specific error Virtualbox throws is:

An error has occurred during virtual machine execution! The error details 
are shown below. You may try to correct the error and resume the virtual 
machine execution.
The I/O cache encountered an error while updating data in medium 
(rc=VERR_INVALID_HANDLE). Make sure there is enough free space on the disk 
and that the disk is working properly. Operation can be resumed afterwards. 

Error ID: BLKCACHE_IOERR 
Severity: Non-Fatal Error

The Void host is using the XFS file system. Not sure if that makes a 
difference (I read about a bug a few years back in the Linux kernel which 
results in EXT4 users also needing Host I/O Cache enabled, and wonder if 
it's related).

Anyone else encountered this issue?

Enabling Host I/O Cache is an acceptable workaround (certainly not a 
deal-breaker), but I would prefer to determine the cause of the issue, and 
solve it there.
I had disabled it to save on some resources. I'm runnning everything from 
an SSD, so things are fast enough that I'd rather avoid some of the 
performance and reliability pitfalls which might occur from using the I/O 
cahce with multiple VMs running simultaneously.

I'm not certain, just yet, if it's a kernel issue, or if the 
virtualbox-ose/virtualbox-ose-dkms XBPS package needs an update. I already 
tried a force-reinstall of the dkms package.
The only thing which corrects the issue is enabling Host I/O Cache.

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