64bit guest on a 32bit host

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64bit guest on a 32bit host

Postby vangop » 24. Dec 2011, 08:47

Hi!
I have 32bit host and I can't run 64bit guest.
Host is ubuntu 11.10 on dell d630.
I get smth like "x64 cpu required but only i686 found". I HAVE enabled the vt in BIOS and in the VM settings. I have
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HWACCM: VMX enabled!
in the logs
So it seems I've met all the requirements, but still have the issue.
Thx!
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Re: 64bit guest on a 32bit host

Postby mpack » 24. Dec 2011, 12:59

Support for 64bit guests requires CPU virtualization support in the host, A.K.A. VT-x (or AMD-v). You need to verify that your CPU has this feature (use google). Intel used to think of this as a premium feature so only found on higher end chips. If the feature exists in the CPU, then it may need to be enabled in the BIOS, as in many cases it is disabled by default. Tweaking the BIOS would involve pressing Del or F10 or something like that as your PC begins to boot up. There's usually a very brief message telling you the correct key. Once in, you would need to find an option which says something like "Virtualization technology: disabled", and make sure it is enabled. Remember to save changes. Finally, make sure the VT-x option is selected in your VM recipe.

One final note: 64bit or not, the only memory the guest can access is memory loaned to it by the host, hence it can't use any memory the host doesn't know about - i.e. it can't use memory from above the 4GB region.
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Re: 64bit guest on a 32bit host

Postby vangop » 24. Dec 2011, 16:34

Like I said in the 1st post, VT is enabled in BIOS. Moreover, it is recognized by the virtualbox which is identified by the log entry I have added and a small v letter in the VM's status line. see dl.dropbox(.)com/u/20461706/screens/vm-vt-x.png
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Re: 64bit guest on a 32bit host

Postby Perryg » 24. Dec 2011, 16:40

Why not post the complete guest log file (as an attachment)?
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Re: 64bit guest on a 32bit host

Postby vangop » 24. Dec 2011, 18:09

Ok, full log attached
Attachments
VBox.log
(71.29 KiB) Downloaded 744 times
Last edited by vangop on 24. Dec 2011, 18:11, edited 1 time in total.
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Re: 64bit guest on a 32bit host

Postby Perryg » 24. Dec 2011, 18:10

Nope post here as an attachment.
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Re: 64bit guest on a 32bit host

Postby Perryg » 24. Dec 2011, 18:39

It appears that you have not set the VT-x bit in VirtualBox and you are running VirtualBox 4.1.2_Ubuntu r38459 linux.x86 version, which does not support 64-bit IIRC at all.
You might try to reinstall to see if it will enable the 64-bit execution bit. Then it might work. You also need to check to see that the bit is enabled in the processor section of the guest settings or you will not be able to run/install the 64-bit guest.

In Linux you don't get a multiarch install, you pick one or the other so here again since the host OS is 32-bit it may not allow you to install the AMD64 version of VirtualBox

Keep in mind (as explained in your VirtualBox users manual) that there is significant overhead when running 64-bit guests on a 32-bit host.


Also it would be helpful if you created a ticket at bugtracker and include the following since your keyboard layout is not recognized. Or just attach the complete log file as indicated below.
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00:00:00.561 Your keyboard layout does not appear to be fully supported by
00:00:00.561 VirtualBox. If you would like to help us improve the product,
00:00:00.561 please submit a bug report and attach this logfile.
00:00:00.561 (Note: please ignore this if you are using a custom layout.)
00:00:00.561
00:00:00.561 The correct table for your layout is:
00:00:00.561 "`~","1!","2@","3#","4$","5%","6^","7&","8*","9(","0)","-_","=+",
00:00:00.561 "qQ","wW","fF","pP","gG","jJ","lL","uU","yY",";:","[{","]}",
00:00:00.561 "aA","rR","sS","tT","dD","hH","nN","eE","iI","oO","'\"","\\|",
00:00:00.562 "zZ","xX","cC","vV","bB","kK","mM",",<",".>","/?","-_","\x0\x0","\x0\x0"


As a side not you would have a lot better performance if the host was 64-bit as well.
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Re: 64bit guest on a 32bit host

Postby vangop » 24. Dec 2011, 19:47

Thanks for the reply,
but I'm confused. From the FAQ, regarding the 64bit guests
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Q: Does VB support 64 bit guests?
A: Support for 64 bit guests was introduced at version 2.0.0. If you wish to create 64 bit guests then we recommend that you upgrade to the latest version. Note that VirtualBox also supports 64-bit guest operating systems, under the following conditions:

    You need a 64-bit processor with hardware virtualization support (see User Manual chapter 1.2, Software vs. hardware virtualization (VT-x and AMD-V), page 10) and a 64-bit host operating system.
    NOTE: Since version 2.1.0, you can run 64 bit Guests while running a 32 bit Host. The prior requirement for Operating System is only for version 2.0.x. You still need the proper hardware.
    You must enable hardware virtualization through your BIOS; software virtualization is not supported for 64-bit VMs.
    Note: some HP BIOSES have a glitch, When You ENABLE VT-X/AMD-V, You DISABLE it, so do try both ways.

In particular:
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NOTE: Since version 2.1.0, you can run 64 bit Guests while running a 32 bit Host.

What do you mean saying that VB 4x doesn't support 64bit? Do you mean that I need to install 64bit vbox onto the 32bit OS?
My CPU meets all the req-s, I've enabled VT in bios, I've enabled vt in VM in the system settings. All that according to the faq entry, should make me happy. Is the faq outdated?
Thanks!
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Re: 64bit guest on a 32bit host

Postby Perryg » 24. Dec 2011, 20:11

I'm saying that I know of no way to run 64-bit guests on 32-bit Linux, regardless of what the manual says. If you look further in the manual "known issues" it states *some* which I take to mean the multiarch versions.

When you installed you VirtualBox from here you choice of one or the other (x86 or AMD64). If you install from your repo it picks the one to fit your OS. Windows VBox is multiarch and probably why it works.

What happens if you try to install the 64-bit version of VirtualBox? (AMD64)

Could I be wrong? Maybe but you do not have 64-bit libraries in most 32-bit Linux host. I also know you must enable IO/APIC and you must be able to enable VT-x/AMD-v support.

PS I didn't say VB 4x doesn't support 64bit I said the version VirtualBox 4.1.2_Ubuntu r38459 linux.x86 is not AMD64
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Re: 64bit guest on a 32bit host

Postby vangop » 25. Dec 2011, 08:55

Thanks for the reply. I wasn't saying u were wrong, rather asking if the faq was dated/incomplete.
The fact that following the faq I'm not able to run 64bit VM hints that u're right :)
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Re: 64bit guest on a 32bit host

Postby Perryg » 25. Dec 2011, 15:49

Like i said I could be wrong. I have just never been able to make it work properly on a Linux host.
But I still say that if you run Linux there is not reason to not use the 64-bit version if your hardware will not support it because it is so much faster.
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