Like most others, if you tried installing Windows 8.1 or Windows Server 2012 R2 64Bit in Oracle Virtualbox, you must have encountered the following error.
This error occurs when the instruction CMPXCHG16B is disabled in your CPU. It is so by default in Oracle Virtualbox. The simple solution is to enable this instruction & then you should not get the error on initializing the Windows 8.1/Windows 2012 virtual machine.
To do this on your linux system first issue the following command,
$VBoxManage list vms
The above command will list all the virtual machines present. Be sure to run this command as a normal user. You won’t see a list of vm’s if the command is executed as a root. The VboxManage command is case-sensitive, keep that in mind. So make sure you use it properly as VboxManage.
Once done, copy down the vms name. In my case “Windows”.
[shuttertux@localhost ~]$ VBoxManage list vms
Now to enable the CMPXCHG16B CPU instruction one needs to execute,
$VBoxManage setextradata “Windows” VBoxInternal/CPUM/CMPXCHG16B 1
The value ‘1’ at the end of the command enables the desired CPU instructions. Now you can go ahead successfully and install Windows 8.1/Windows 2012 64Bit in Oracle VirtualBox.
The wikipedia explains the following on CMPXCHG16B CPU instructions:
Early AMD64 processors lacked the CMPXCHG16B instruction, which is an extension of the CMPXCHG8B instruction present on most post-80486 processors. Similar to CMPXCHG8B,CMPXCHG16B allows for atomic operations on octal words. This is useful for parallel algorithms that use compare and swap on data larger than the size of a pointer, common in lock-free and wait-free algorithms. Without CMPXCHG16B one must use workarounds, such as a critical section or alternative lock-free approaches. This also prevents 64-bit Windows from having a user-mode address space larger than 8 terabytes. The 64-bit version of Windows 8.1 requires this feature.
Having a tripod helps in capturing sharp & steady photographs. However, it is just as crucial to know how to setup a tripod properly to get the steady photographs in the first place. Even with a tripod, photos can come out shaky/blurry if one does not pays proper attention to its setup.
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Couple of weeks ago, Mumbai witnessed high tides near the coast. Certain areas close to the shore were completely inundated with water as mammoth tides broke free with all their might. I was a witness to the nature’s fury & made some journalist style photographs.
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As photographers, we all know that light is better when it is comes from behind the subject than from the front. Most of us like to capture our portrait with the setting sun in the backdrop once we are at the beach or some sunset point. However, not many like the outcome photograph in such a situation. This is because, either the person comes out dark or he/she appears too bright and the background is burnt.
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I love high speed photography & water splashes fascinate me. A few days ago, I decided to get myself splashed with cold water in this hot summer. The results were amazing!
As you can see from the diagram, I took this photograph in a confined space, in my bathroom. I rested the camera on tripod which was just an arm’s length away. A couple of feet to my left was my speedlight with a gobo aimed directly at me without any modifier. The gobo made sure the background was sufficiently dark. The reflector you see in the diagram was the white wall of the bathroom.
Taking the Photograph:
Camera Setting : Aperture – f/6.3, Shutter Speed – 1/200th, ISO 100, Focal Length – 28mm.
For such a photograph in confined space, I was more careful of not wetting my camera and flash. Here, the timing was the key. I had the camera on 10 seconds self-timer & I had to make a splash on my face just at the same time. Its convenient if you have someone to throw water over you. However, after some 10 splashes, I eventually found out the above photograph to be perfect. The formation of water is perfect & so are my expressions. A splash like this hits you hard & as the water enters your nostrils to irritate, getting the right expressions is challenging.
After the RAW processing, I cloned out the tiles pattern in GIMP to get a clear non-obtrusive background. I bumped up the contrast & even applied an unsharp mask. Next, I applied some vignette. Finally, I converted this to Black & White as I wanted it to be.
That’s it & I had my photograph!