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Intel Fixes VT-d Bug in Sandy Bridge-E CPUs

by - source: Intel PCN

Intel will be shipping its i7-3960X Extreme Edition and i7-3930K processor in C2 stepping in January, the company revealed in a product change notification (PCN) this week.

The C2 stepping removes the VT-d bug in C1 CPUs, which affected the CPU's hardware accelerated virtualization support.

While C1 CPUs are only running the software-accelerated only mode, the C2 now properly supports hardware acceleration on a hosted OS, Intel said. According to the document sent out on December 9, samples of the C2 Sandy Bridge-E processors became available last week. Commercial retail and tray units will begin shipping on January 20.

Intel told its customers that it does not anticipate "change to customer platforms designed to Intel guidelines." However, if a customer chooses to enable Intel VT-d, "regression testing is recommended to ensure their board is properly enabled," the PCN states. Those customers who prefer their own BIOS will have to install the latest Microcode update to support the C2 stepping.

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soldier37 12/14/2011 12:09 PM
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applefairyboy 12/14/2011 1:04 AM
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mouse24 12/14/2011 1:20 AM
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mouse24 12/14/2011 1:21 AM
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mouse24 :
I am confused, what exactly is VT-d and whats wrong with there being no hardware acceleration? isnt the gpu normally handling that?



edit: unless they mean it adds virtualization hardware accel support for virtual cores while running multi threaded apps...

bejabbers 12/14/2011 1:38 AM
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Is this something that Intel will replace my c1 with? Or are they saying that everyone with the c1 is out off luck.

dgingeri 12/14/2011 1:46 AM
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mouse24 :
I am confused, what exactly is VT-d and whats wrong with there being no hardware acceleration? isnt the gpu normally handling that?



VT-d is hardware acceleration within the CPU for virtual machines. it has nothing to do with graphics. This is mostly used for (in home and/or regular user situations) virtual machines to run old software that won't run under the current OS, like running Windows XP software in a Windows XP virtual machine while the main OS is Windows 7, or running a Linux virtual machine on a Windows main OS. Most people won't be using it. If they do, VT-d won't make much of a difference for most people.

I do, however. I use it to make multiple virtual machines to learn stuff for IT certifications. Right now, I'm working on my MCITP-VA cert, running multiple virtual machines from my home server (running Windows 2008 R2) so I can get a better job. VT-d missing would mean great trouble for me, if I were to use it as a server. Thankfully, if I were to get one, I wouldn't be using it as a server since I already have that.

gtx_560tiuser 12/14/2011 1:50 AM
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well at least they fixed it :P

SteelCity1981 12/14/2011 2:17 AM
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For the typical pc user they don't even know what VT-d does let alone use it.

molo9000 12/14/2011 3:20 AM
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SteelCity1981 :
For the typical pc user they don't even know what VT-d does let alone use it.



The typical PC user doesn't buy a $1000 CPU.

Pinhedd 12/14/2011 4:13 AM
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dgingeri :
VT-d is hardware acceleration within the CPU for virtual machines. it has nothing to do with graphics. This is mostly used for (in home and/or regular user situations) virtual machines to run old software that won't run under the current OS, like running Windows XP software in a Windows XP virtual machine while the main OS is Windows 7, or running a Linux virtual machine on a Windows main OS. Most people won't be using it. If they do, VT-d won't make much of a difference for most people.I do, however. I use it to make multiple virtual machines to learn stuff for IT certifications. Right now, I'm working on my MCITP-VA cert, running multiple virtual machines from my home server (running Windows 2008 R2) so I can get a better job. VT-d missing would mean great trouble for me, if I were to use it as a server. Thankfully, if I were to get one, I wouldn't be using it as a server since I already have that.



That is not entirely correct.

VT-x is the set of extensions required to properly secure a virtual machine running in long addressing mode and reduce VM reliance on operation emulation. It is the bare minimum required to run an OS safely in 64 bit mode on Intel CPUs (AMD CPUs can run 64 bit guest OSes purely in software but will still see performance benefits from AMD-V).

VT-d and AMD-Vi are the sets of extensions required to properly allow a guest OS access to peripherals without having to go through a software layer. This allows guests to access Ethernet controllers, USB controllers, PCI-E controllers, SATA controllers, etc... VT-d is to the chipset as VT-x is to the CPU.

digitalrazoe 12/14/2011 4:32 AM
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~And so it begins ... BugZilla

A Bad Day 12/14/2011 5:04 AM
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notsleep 12/14/2011 5:25 AM
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...or a guy spending $4,000 on a laptop for his wife to surf the net with...early adopters are usually not that bright...

trialsking 12/14/2011 5:33 AM
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notsleep :
...or a guy spending $4,000 on a laptop for his wife to surf the net with...early adopters are usually not that bright...


but it loads the pages SOOOOOO much faster

De5_roy 12/14/2011 9:03 AM
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:) intel is doing a good job keeping their buggy cpu away from strict media scrutiny and rolling out the new revision so early.
if amd had it.......it could become a much bigger deal...

JimmiG 12/14/2011 10:51 AM
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Wow, that's a pretty serious flaw for the affected users that need it. Surprised we haven't heard much about this before. VT-d or AMD-Vi are absolutely essential for me.

CyberAngel 12/14/2011 11:33 AM
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Looks like even Windows 8 does not use it
or rather I could not quickly find in on the docs currently available for W8
Maybe it comes along later or I was sloppy
Those of you who have a greater tendency to load every doc available (of W8)
may correct this (possible misinfo), please

digiex 12/14/2011 12:13 PM
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This is the perennial problem to early adapters, bugs...

Pinhedd 12/14/2011 12:29 PM
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CyberAngel wrote :

Looks like even Windows 8 does not use it
or rather I could not quickly find in on the docs currently available for W8
Maybe it comes along later or I was sloppy
Those of you who have a greater tendency to load every doc available (of W8)
may correct this (possible misinfo), please




Windows 8 is not a virtualization platform. Most hypervisor based virtualization platforms are focused on resource allocation and consolidation efficiency, and so the server oriented Hyper-V probably wouldn't get any real advantage from VT-d and so I doubt that they would implement it yet.

Anonymous 12/14/2011 1:11 PM
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In other news, the same CPU is still an 8-core with 2 perfectly good cores intentionally disabled, not die harvested like another company would do, as every Intel chip on every wafer is flawless, bug free, and capable of 5ghz on air.

Furthermore, most people who would buy this CPU just want a smoother Facebook experience, not to use as a professional workstation to run those virtual machine thingies, whatever they are. They wouldn't be disappointed at all to pay $1000 for a CPU that has vastly inferior VM performance to a $200 Bulldozer CPU due to lack of proper IO acceleration.

lradunovic77 12/14/2011 4:30 PM
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I received latest ASRock update for C2 and i enabled VT-d on my C1 processor and everything works fine. With proper BIOS update it should be good on C1 CPUs as well.

ochentay4 12/14/2011 5:03 PM
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gtx_560tiuser :
well at least they fixed it


They did not fixed it. Everyone who has a C1 processor is screwed. Thanks god I read this news because I was trying to make a decision between i7-2600 or i7-3960X.

They should offer an exchange them for free (or at least for a shrot fee) because C1 are DEFECTIVE UNITS (like previous TLB fckup on Phenom1).

lradunovic77 12/14/2011 5:06 PM
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With latest BIOS update i enabled it and i have no problems fully using VT-d on my C1. I do lot of virtualization among other things like programming and gaming and i7 i3930K seems running quite happy. Perhaps there are cases where VT-d won't work but i believe with proper Bios update should fix for most people. Again most people don't even use VT-d, it enabled virtualized OS to directly access things like video card so you could basically run Crysis 2 game in there :).

eddieroolz 12/15/2011 12:15 PM
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Good thing (for Intel that is) that the issue only affected their minor-volume sales product. Imagine if the problem was with Ivy Bridge - it would be the Phenom TLB debacle all over again.

emike09 12/15/2011 7:41 PM
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I just spoke with an Intel rep about this - the issue likes in the BIOS, NOT the CPU iteslf. Each manufacturer should be releases a BIOS update that fixes this issue. C2 CPU's have it fixed in-processor. Nobody is screwed, just contact your MB Manufacturer and get the latest BIOS.

Anonymous 12/17/2011 7:38 AM
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Thank goodness I didn't get that 3930k to run Xen on then...

fellow 02/08/2012 9:05 AM
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lradunovic77 and emike09-- I can't believe this is only in the BIOS, since Intel's ARK shows VT-d is unavailable for these chips now. Can someone please follow up on this article, now that the C2 is out for two plus weeks? I would very much like to know if VT-d is working.

rjos 02/12/2012 5:51 PM
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Yes, the ark site doesn't show VT-d available on these. What's up? Is there a way to get a list of CPUs and boards that support VT-d?

rjos 02/12/2012 5:51 PM
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Yes, the ark site doesn't show VT-d available on these. What's up? Is there a way to get a list of CPUs and boards that support VT-d?

fellow 02/12/2012 8:52 PM
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After more research, I think Intel intentionally disables VT-d on K parts. Looks like we cannot have unlocked multiplies and VT-d. Seems arbitrary and illogical, considering the premium paid for enthusiast chips.

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