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can I not use vt-d for kvm vm?


xxredxpandaxx

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One of three things:

 

Your motherboard doesn't truly support virtualization (some mobos claim support but fail to deliver), there is another setting somewhere in your bios that you are missing, or your motherboard may have a BIOS update to fix this problem.

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my processor has it, its an i5 4590s I only see an option for vt-d in my bios and I have it enabled but when I go to the vms page in unraid it says i don't have it.

 

Your CPU clearly supports both vt-x and vt-d.    Your BIOS likely provides a mechanism to enable/disable it.  Probably not labeled "vt-x" -- likely simply shows "virtualization" or "virtualization technology" and has an enabled/disabled choice.    Look carefully  :)  [since it has an on/off setting for vt-d, it almost certainly has a similar setting for virtualization]

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my processor has it, its an i5 4590s I only see an option for vt-d in my bios and I have it enabled but when I go to the vms page in unraid it says i don't have it.

 

Your CPU clearly supports both vt-x and vt-d.    Your BIOS likely provides a mechanism to enable/disable it.  Probably not labeled "vt-x" -- likely simply shows "virtualization" or "virtualization technology" and has an enabled/disabled choice.    Look carefully  :)  [since it has an on/off setting for vt-d, it almost certainly has a similar setting for virtualization]

 

It would be pretty odd if the mobo let you toggle vt-d independent of vt-x, but I guess I have seen stranger things in a BIOS before ;-)

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Agree ... you can turn it off if you are sure you won't need it.    While it shouldn't make any difference if you simply leave it on (so if you ever DO decide to try pass-through, you won't forget that it's turned off and spend time figuring out what's wrong).    Every once in a while, some esoteric issue can arise that requires some of the extended features to be disabled -- vt-d, vt-x, hyperthreading, etc.    But I haven't heard of anything in UnRAID that has this issue.

 

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Agree ... you can turn it off if you are sure you won't need it.    While it shouldn't make any difference if you simply leave it on (so if you ever DO decide to try pass-through, you won't forget that it's turned off and spend time figuring out what's wrong).    Every once in a while, some esoteric issue can arise that requires some of the extended features to be disabled -- vt-d, vt-x, hyperthreading, etc.    But I haven't heard of anything in UnRAID that has this issue.

 

Wasn't there some oddball SATA controller (marvell or something) that had issues with VT-d enabled?

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Certain Marvell controllers have had this, and it has to do with the IOMMU and not following the proper addressing or ram assignments that cause the issue.

 

Probably doesn't have good support for IOMMU DMA remapping.  IOMMU "tricks" devices by essentially doing the equivalent of NAT but for memory mapping.  So the device thinks it's writing to a certain address space, but then IOMMU is supposed to translate that request to a different physical address space to avoid overlapping with other IOMMU bound devices.  Bottom line:  some devices just don't follow the standards the rest of the industry creates and when that happens, weirdness can occur.

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  • 2 weeks later...

So do I understand this correctly?

I can experiment with VM's and they should work on my system I just wont be able to pass through hardware as my processor doesn't support vt-d but does support vt-x?

 

i3-550 #BX80616I3550 on a SUPERMICRO MBD-X8SIL-F

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So do I understand this correctly?

I can experiment with VM's and they should work on my system I just wont be able to pass through hardware as my processor doesn't support vt-d but does support vt-x?

 

i3-550 #BX80616I3550 on a SUPERMICRO MBD-X8SIL-F

 

Yes

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So do I understand this correctly?

I can experiment with VM's and they should work on my system I just wont be able to pass through hardware as my processor doesn't support vt-d but does support vt-x?

 

i3-550 #BX80616I3550 on a SUPERMICRO MBD-X8SIL-F

 

Yes

 

Thanks!

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So do I understand this correctly?

I can experiment with VM's and they should work on my system I just wont be able to pass through hardware as my processor doesn't support vt-d but does support vt-x?

 

i3-550 #BX80616I3550 on a SUPERMICRO MBD-X8SIL-F

 

Yes

 

Thanks!

 

Most definitely.  You might be interested in this video:

 

 

I show what you can do with a low-end unRAID system (Celeron processor, 4GB of RAM) and streaming Windows virtual desktops.  VT-d is awesome, don't get me wrong, but you can do quite a bit still without it.

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So do I understand this correctly?

I can experiment with VM's and they should work on my system I just wont be able to pass through hardware as my processor doesn't support vt-d but does support vt-x?

 

i3-550 #BX80616I3550 on a SUPERMICRO MBD-X8SIL-F

 

Yes

 

Thanks!

 

Most definitely.  You might be interested in this video:

 

 

I show what you can do with a low-end unRAID system (Celeron processor, 4GB of RAM) and streaming Windows virtual desktops.  VT-d is awesome, don't get me wrong, but you can do quite a bit still without it.

Thanks jonp looking forward to learning how to do this and having some fun along the way. Exciting times.

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