Linux allows this mobo 2x RAM XP shows; can I VM XP and split it?
August 1, 2008 11:15 AM   Subscribe

Would this OS/RAM/VM trick work, you think? Linux seems to allow this PC mobo double the RAM XP shows as possible; can I VM XP on a Linux host and split the RAM between the two?

When under Windows, a RAM compatibility scan says the max installable is 2gb. Run the same scan (the Crucial Memory scanner) under Ubuntu, max comes out as 4gb instead. Makes me believe there's a difference between the mobo and XP's capabilities.

I'd like to have a 2gb RAM Ubuntu system and a 2gb RAM XP system to switch back and forth between, while they're running simultaneously (so dual-boot is out). 2 separate boxes with a KVM switch would be awkward due to space constraints, etc.

So if I installed Ubuntu as the OS, put in 4gb RAM, then set up an XP virtual machine running in VMware, can I assign the XP VM 2gb and leave 2gb for Ubuntu? Anything tricky about that, or that I should watch out for?

A little new for me to mix the 3 things, I also haven't done any complex memory assigning before. I've got little enough hair left that I'd prefer not to pull any more out trying to get this to work, so I figured I'd ask the smartest people I know before I get into it. Thanks, MeFites!
posted by penciltopper to Computers & Internet (10 answers total)
Have you checked on the motherboard manufacturers website? As this sounds like it could simply be a problem with the crucial tool more than anything.

XP does not start having memory issues until you hit the 4Gb mark.
posted by moochoo at 11:29 AM on August 1, 2008

32 or 64 bit Ubuntu? Because an unmodified 32-bit Ubuntu install will only see about 3.2 Gigs of that 4GB memory.

I currently have 4 GB memory in my 32bit Ubuntu (8.04) box (of which it only sees 3.2GB), and have an XP install in VMware Workstation 5.5 assigned 1.5 GB memory through the VMWare application. Works like a dream, no issues here. (Well, except that I can't the Windows VM to talk to my networked printer, but I couldn't be bothered spending more than 10 mins trying.)

I have no idea why the scanner is reporting different values for each OS, tho.
posted by cgg at 11:29 AM on August 1, 2008

VMware is very simple to configure so there's no real issues there. I would be worried that the Linux memory scan tool is wrong. Do you not have a manaual for the mobo? What the make & model?
posted by GuyZero at 11:29 AM on August 1, 2008

I was under the impression that 32 bit XP could only address ~3 gigs of ram and to utilize anything above you would need 64 bit installed which cgg mentions in the context of linux.

In response to your question though, I would ignore the tool and look at specific info on the mobo in question to see what it can handle (most modern ones could handle 4 w/o issue I would suspect) and go from there keeping in mind the 32/64 bit OS issue.
posted by zennoshinjou at 12:14 PM on August 1, 2008

Response by poster: It's a recycled/inherited PC, so I have zero documentation.
But I found a tool to check the motherboard and it tells me:

Board: Lite-On Tech. 08FCh D01
Serial Number: 21811571601267
Bus Clock: 133 megahertz
BIOS: American Megatrends Inc. 1.15 4/13/2005

How/where would I look up the true capabilities RAM-wise?
Answers above seem to imply that the RAM scanner is not right.
posted by penciltopper at 12:27 PM on August 1, 2008

Response by poster: oh, and it's an HP DX2000, with a 2.8 ghz Pentium 4, if that counts.
The idea was to run 32-bit Ubuntu hosting 32-bit XP VM, with 2gbRAM (or close) allocated to each. If 32-bit of either will only see 3.2gb RAM, I suppose I could live with 1.5gb to each if that works.
posted by penciltopper at 12:35 PM on August 1, 2008

Is it an HP? This guy has a similar motherboard and this compatibility chart indicates a 4GB maximum for that machine. Hardly conclusive but it's a start. Get 2G of ram from Best Buy or something, see if it boots/works and take it back if not. Modulo the 32-bit memory hole issue it seems like it ought to work.
posted by Skorgu at 12:40 PM on August 1, 2008

Err d'oh. Yes you'll 3.whatever GB of real ram to play with. Also be aware that Linux will happily overcommit your memory and end up swapping VMWare's ram to disk if you beat the host system up a lot. This will make windows Very Unhappy, but there's not much to be done about it.
posted by Skorgu at 12:43 PM on August 1, 2008

The amount of ram that you will be able to use with a 32 bit operating system (assuming you're NOT using PAE which you probably aren't) will depend on a lot of things, mostly the peripherals you have installed and how much memory-mapped address space they require. So, no one will be able to tell you exactly because it depends on too many factors, but it is usually given as between 2.5 and 3.5 gigabytes.
posted by Rhomboid at 2:01 PM on August 1, 2008

If you want more details on how this works read this article.
posted by Rhomboid at 2:06 PM on August 1, 2008

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