Virtualization Hardware drivers and devices

Emulated devices
Emulated devices, sometimes referred to as virtual devices, exist entirely in software. Emulated device drivers are a translation layer between the operating system running on the host (which manages the source device) and the operating systems running on the guests. T he device level instructions directed to and from the emulated device are intercepted and translated by the
hypervisor. Any device of the same type as that being emulated and recognized by the Linux kernel is able to be used as the backing source device for the emulated drivers. 

Para-virtualized Devices
Para-virtualized devices require the installation of device drivers on the guest operating system providing it with an interface to communicate with the hypervisor on the host machine. T his interface is used to allow traditionally intensive tasks such as disk I/O to be performed outside of the virtualized environment. Lowering the overhead inherent in virtualization in this manner is
intended to allow guest operating system performance closer to that expected when running directly on physical hardware.

Physically shared devices
Certain hardware platforms allow virtualized guests to directly access various hardware devices and components. T his process in virtualization is known as passthrough or device assignment. Passthrough allows devices to appear and behave as if they were physically attached to the guest operating system.

Comments

Post a Comment

Popular posts from this blog

KVM & Qemu

QEMU is a powerful emulator, which means that it can emulate a variety of processor types. Xen uses QEMU for HVM guests, more specifically for the HVM guest's device model. The Xen-specific QEMU is called qemu-dm (short for QEMU device model) QEMU uses emulation; KVM uses processor extensions (intel-VT) for virtualization. Both Xen and KVM merge their various functionality to upstream QEMU, that way upstream QEMU can be used directly to accomplish Xen device model emulation, etc. Xen is unique in that it has paravirtualized guests that don't require hardware virtualization. Both Xen and KVM have paravirtualized device drivers that can run on top of the HVM guests. The QEMU hypervisor is very similar to the KVM hypervisor. Both are controlled through libvirt, both support the same feature set, and all virtual machine images that are compatible with KVM are also compatible with QEMU. The main difference is that QEMU does not support native virtualization. Consequently, QEMU has ...
Read more

PHP Fatal error: Class 'JFactory' not found

I have faced this issue in Joomla site and searched the forums but none of the forums including joomla did not give solution for me. They simply suggest to check joomla version, php version compatibility and php extensions. Finally I have fixed the issue. Issue:- ---------  [26-Sep-2014 18:11:29 Europe/Berlin] PHP Fatal error: Class 'JFactory' not found in /home/test/public_html/index.php on line 31 Cause & Solution:- ----------------------- In my case, it seems file which gives the class JFactory was missed. /home/test/public_html/libraries/joomla/factory.php --->Core file for Joomla. Simply restore that file under proper path to fix the issue.
Read more

docker.errors.APIError: 400 Client Error client is newer than server

You can face this issue when you are trying to use docker python library. Error: docker.errors.APIError: 400 Client Error: Bad Request for url: http+docker://localunixsocket/v1.26/images/json?only_ids=0&all=0 ("client is newer than server (client API version: 1.26, server API version: 1.24)") Solution: client= docker.from_env(version='auto') Use parameter "version" when instantiating a client.
Read more