Skip to main content

VMware ESX: Enhanced VMotion Compatibility

The classic VMotion problem of recent times is the customer who buys tin from a vendor, only to find out that the processor number e.g. 53xx and 54xx, is actually quite significant. The principle difference which will prevent VMotion is the addition of SSE4.1 to the 54xx range of Intel processors (if you previously only had 53xx Intel processors).

An application using the SSE4.1 feature (or is aware of this feature) when VMotioned to a non-SSE4.1 host would likely blue screen trying to make use of this feature on the older host.

People then recalled the CPU mask feature in VMware - we’ll just mask it out they thought. Unfortunately VMware declared this was an unsupported mask with KB1993 and KB1991.

Note that for production environments, VMware neither supports nor recommends modifying VMotion masks for SSE3, SSE3, or SSE4.1 because of the risk of failure of the application or guest operating system after migration.

The reason soon became clear:

* SSE features can be used by user-level code (applications).
* Mask does not work for user-level code (i.e. applications).
* In user-level code, CPUID is executed directly on hardware and is not intercepted by VMware.
* Thus, VM cannot reliably hide SSE from an application
Good stuff, find out more at the source blog.
Labels:

Comments

Post a Comment

Popular posts from this blog

Security: VMware Workstation 6 vulnerability

vulnerable software: VMware Workstation 6.0 for Windows, possible some other VMware products as well type of vulnerability: DoS, potential privilege escalation I found a vulnerability in VMware Workstation 6.0 which allows an unprivileged user in the host OS to crash the system and potentially run arbitrary code with kernel privileges. The issue is in the vmstor-60 driver, which is supposed to mount VMware images within the host OS. When sending the IOCTL code FsSetVoleInformation with subcode FsSetFileInformation with a large buffer and underreporting its size to at max 1024 bytes, it will underrun and potentially execute arbitrary code. Security focus
Post a Comment
Read more

OS Virtualization comparison: Parallels' Virtuozzo vs the rest

Virtuozzo's main differentiators versus hypervisors center on overhead, virtualization flexibility, administration and cost. Virtuozzo requires significantly less overhead than hypervisor solutions, generally in the range of 1% to 5% compared with 7% to 25% for most hypervisors, leaving more of the system available to run user workloads. Customers can also virtualize a wider range of applications using Virtuozzo, including transactional databases, which often suffer from performance problems when used with hypervisors. On the administration side, customers need to manage, maintain and secure just a single OS instance, while the hypervisor model requires customers to manage many OS instances. Of course, the hypervisor vendors have worked hard to automate much of this process, but it still requires more effort to manage and maintain multiple operating systems than a single instance. Finally, OS virtualization with Virtuozzo has a lower list price than the leading hypervisor for comme...
Post a Comment
Read more