Why is AMD-V disabled?

Discussions related to using VirtualBox on Windows hosts.

Why is AMD-V disabled?

Postby eeppeliteloop » 5. May 2011, 09:28

Hi. I am using VirtualBox 4.0.6 (as an "administrator") on a Windows 7 64-bit host with Debian 32-bit and WinXP 32-bit guests. For both of them, I enabled AMD-V support. When I launch any of them, I see that AMD-V is not active. Yesterday, I was still using WinXP 32-bit on the same computer, with VirtualBox 4.0.6, and with the same guests (actually I created new ones but I mean with the same guest systems), AMD-V was active (it's enabled in the BIOS and everything; it worked yesterday).

Is it the 32-bit to 64-bit transition? Is it something special regarding Windows 7? May AMD-V be enabled when virtualizing a 32-bit guest on a 64-bit host?

Please help, I'm clueless.

Thank you,
eeppeliteloop
 
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Re: Why is AMD-V disabled?

Postby BillG » 5. May 2011, 12:18

Whether hardware virtualization is enabled or not depends entirely on your hardware and you BIOS. It is not affected by what OS you are running. Check the BIOS settings again.

32-bit guests will run without it. 64-bit guests will not.
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Re: Why is AMD-V disabled?

Postby eeppeliteloop » 5. May 2011, 19:57

I double-checked my BIOS and Virtualization is enabled. Also, the AMD-V Hyper-V Compatibility Check Utility tells me AMD-V is enabled and functional. However, when I launch a guest, the AMD-V icon in the bottom status bar says it's disabled. Why?
eeppeliteloop
 
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Re: Why is AMD-V disabled?

Postby BillG » 6. May 2011, 06:22

Is it enabled here?

VT.PNG
VT.PNG (39.01 KiB) Viewed 4959 times
BillG
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Re: Why is AMD-V disabled?

Postby Sasquatch » 7. May 2011, 13:28

If it is, post a log so we can see where the problem lies. The log usually shows what's wrong.
Read the Forum Posting Guide before opening a topic.
VirtualBox FAQ: Check this before asking questions.
Online User Manual: A must read if you want to know what we're talking about.
Howto: Install Linux Guest Additions
Howto: Use Shared Folders on Linux Guest
See the Tutorials and FAQ section at the top of the Forum for more guides.
Try searching the forums first with Google and add the site filter for this forum.
E.g. install guest additions site:forums.virtualbox.org

Retired from this Forum since OSSO introduction.
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Re: Why is AMD-V disabled?

Postby Orris » 11. Jan 2012, 01:25

I googled this and found this post which seems a little open ended.

I had the same problem and i found that if you have selected Multiple CPU cores it enables VT-x/AMD-V even if you untick it as an option.
Still not sure why it does it when it is enabled in Bios, but thought i would quickfix for now and figure the rest out later
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