virtualbox.org

Hello,

I've installed ubuntu 9.04 on a virtual machine and tried to increase the number of CPU's, but vbox wouldn't let me - the slider control is disabled and locked on 1 CPU. Why is that?

Do you have more then 1 cpu? vt-x enabled and working?

vbox4me2 wrote:Do you have more then 1 cpu? vt-x enabled and working?

I have q8200 (quad), no problem runnung 2 cpus in vmware. Almost sure v-tx enabled - I checked it when installed vbox - will check again when I'm home.

Thanks

Hi, I have the same problem. My host runs Windows XP on Intel Dual Core CPU, but I am not able to increase number of virtual CPUs from 1 to 2. In some discussions I found an information, that host must support HW virtualization in order the VBOX be able to present more than one CPU. But I didn’t find that information in an official VBox documentation (e.g. I would expect it in User Manual – chapter 3.7.2.2 ). In my guest configuration is VT-x/AMD-V enabled by default, but my HW doesn't support HW virtualization. Is that the reason of my problem?

If vt-x is not working then no smp won't work either, see the quickclick faq for links to testpages and other stuff about checking vt-x functionality.

Ondrej wrote:Hi, I have the same problem. My host runs Windows XP on Intel Dual Core CPU, but I am not able to increase number of virtual CPUs from 1 to 2. In some discussions I found an information, that host must support HW virtualization in order the VBOX be able to present more than one CPU. But I didn’t find that information in an official VBox documentation (e.g. I would expect it in User Manual – chapter 3.7.2.2 ). In my guest configuration is VT-x/AMD-V enabled by default, but my HW doesn't support HW virtualization. Is that the reason of my problem?

I have VT-x/AMD-V checked and disabled (can't turn it off). Not sure what it means.

ForeverNoob wrote:

Ondrej wrote:Hi, I have the same problem. My host runs Windows XP on Intel Dual Core CPU, but I am not able to increase number of virtual CPUs from 1 to 2. In some discussions I found an information, that host must support HW virtualization in order the VBOX be able to present more than one CPU. But I didn’t find that information in an official VBox documentation (e.g. I would expect it in User Manual – chapter 3.7.2.2 ). In my guest configuration is VT-x/AMD-V enabled by default, but my HW doesn't support HW virtualization. Is that the reason of my problem?

I have VT-x/AMD-V checked and disabled (can't turn it off). Not sure what it means.

Is it grayed out but checked? Mine is like that and if you read the manual it will tell you that is default setting now in Virtual Box because so many CPUs now support Hardware virtualization. But if it is grayed out that means that Virtual Box thinks your CPU doesn't have Hardware virtualization.

I have a CPU that Dell promised had Hardware virtualization but it doesn't so I have to use software virtualization only. I read all around the net that VirtualBox would use both my CPUs even though I don't have hardware virtualization. So, that is a main reason I got VirtualBox. I just made my first guest and kept trying and trying to move that slider so it would use both CPUs. It does say this in 1.2 of the User Manual:

"VirtualBox's 64-bit guest support (added with version 2.0) and multiprocessing (SMP, added with version 3.0) both require hardware virtualization to be enabled. (This is not much of a limitation since the vast majority of today's 64-bit and multicore CPUs ship with hardware virtualization anyway; the exceptions to this rule are e.g. older Intel Celeron and AMD Opteron CPUs.)"

I don't know why it says the exception to the rule is older Intel Celeron. I have an Intel Pentium 4 670 processor at 3.8GhZ with hyperthreading and NCQ. That is no celeron! This computer tests faster than many dual core machines that are much, much newer. Dell's mistake in assuring me this processor had hardware virtualization was probably because they were thinking of the 671 that does have it. Intel's site at the time was confusing as it appeared that the 670 had it also. I am disappointed as I was hoping to see both processors in guests made with VirtualBox.

Mele20 wrote:

ForeverNoob wrote:

Ondrej wrote:Hi, I have the same problem. My host runs Windows XP on Intel Dual Core CPU, but I am not able to increase number of virtual CPUs from 1 to 2. In some discussions I found an information, that host must support HW virtualization in order the VBOX be able to present more than one CPU. But I didn’t find that information in an official VBox documentation (e.g. I would expect it in User Manual – chapter 3.7.2.2 ). In my guest configuration is VT-x/AMD-V enabled by default, but my HW doesn't support HW virtualization. Is that the reason of my problem?

I have VT-x/AMD-V checked and disabled (can't turn it off). Not sure what it means.

Is it grayed out but checked? Mine is like that and if you read the manual it will tell you that is default setting now in Virtual Box because so many CPUs now support Hardware virtualization. But if it is grayed out that means that Virtual Box thinks your CPU doesn't have Hardware virtualization.

I have a CPU that Dell promised had Hardware virtualization but it doesn't so I have to use software virtualization only. I read all around the net that VirtualBox would use both my CPUs even though I don't have hardware virtualization. So, that is a main reason I got VirtualBox. I just made my first guest and kept trying and trying to move that slider so it would use both CPUs. It does say this in 1.2 of the User Manual:

"VirtualBox's 64-bit guest support (added with version 2.0) and multiprocessing (SMP, added with version 3.0) both require hardware virtualization to be enabled. (This is not much of a limitation since the vast majority of today's 64-bit and multicore CPUs ship with hardware virtualization anyway; the exceptions to this rule are e.g. older Intel Celeron and AMD Opteron CPUs.)"

I don't know why it says the exception to the rule is older Intel Celeron. I have an Intel Pentium 4 670 processor at 3.8GhZ with hyperthreading and NCQ. That is no celeron! This computer tests faster than many dual core machines that are much, much newer. Dell's mistake in assuring me this processor had hardware virtualization was probably because they were thinking of the 671 that does have it. Intel's site at the time was confusing as it appeared that the 670 had it also. I am disappointed as I was hoping to see both processors in guests made with VirtualBox.

Is it possible that hardware virtualization on my CPU is somehow disabled, maybe in BIOS or something?

A lot of machines with hardware virtualization ship with it disabled in the bios. So, check around in the bios for it. Why OEMs do this I don't know. But then I couldn't figure out why both my XP machines that have hyperthreading CPUs came with it disabled in the bios.

Mele20 wrote: I am disappointed as I was hoping to see both processors in guests made with VirtualBox.

no, this Pentium4 is one processor with two input pipelines and it cant work on both pipelines at the same time. The P4 netburst pipelines are very long and when instructions are out of order the whole pipeline has to be flushed and is lost, hyperthreading can switch to the other pipeline and the processeor still has useful work while the flushed pipeline is rebuild.
I bet you would not get anything more performance by giving both input pipelines to the guest, the host needs processor too and i guess it could lead to excess pipeline flushes when the host has to fight with the guest for processor cycles... anyway, i would not even give both of a real dual core to a guest

ForeverNoob wrote:Is it possible that hardware virtualization on my CPU is somehow disabled, maybe in BIOS or something?

its disabled in the CPU, the Q8200 doesnt have http://processorfinder.intel.com/

ForeverNoob wrote:Is it possible that hardware virtualization on my CPU is somehow disabled, maybe in BIOS or something?

its disabled in the CPU, the Q8200 doesnt have http://processorfinder.intel.com/[/quote]
Ahhh, that's true http://ark.intel.com/Product.aspx?id=36547

Still, in vmware I do get multiple cores. How is that?

Probably they use a different approach to provide SMP to the guest. Probably they are doing it in software, like Qemu does.
Doing it in software should be a lot harder/slower than what VBox does.

OK, thank you all.

MKhaos7 wrote:Probably they use a different approach to provide SMP to the guest. Probably they are doing it in software, like Qemu does.
Doing it in software should be a lot harder/slower than what VBox does.

Thanks for the detailed explanation of the netburst lines in Pentium 4's. I know it is not a real dual core processor but it shows up so frequently in many programs I use as 2 processors. Even Task Manager shows it that way. I was wondering how VMWare Workstation 6/6.5 was handling using two processors. I have Workstation 5.5 and it doesn't have this ability at all. I have been told that my hyperthreading Pentium IV will be seen as dual processors in version 6/6.5. I don't have the money to upgrade though. If it is being done in software then it would slower than what VirtualBox does.