losalamos.redhawk.org

VMWareBios

VMWare uses a very old bios for the guest virtual machines. This implements i/o controls via DMA instead of IOMMU like most Opteron based hardware does. Simulating the DMA is not a bad thing in and of itself, but this bios had the memory hole problem in order to support extremely old operating systems such as Windows 95. To prevent out of memory (OOM kill) problems in SMP linux installations you MUST change the bios and enable the memory hole to address extended memory.

This can be done via the following procedure.

1. Enter the bios for the Guest VM.
Do this when you boot the guest by pressing F2 at the initial boot screen prior to the grub menu.

2. Cursor over to the "Advanced" tab.

3. Cursor down to "Advanced Chipset Control" and press Enter.

4. The first item should be "Enable memory gap:"
This should be by default set to "Disabled".

5. Cursor to if if not highlighted, press Enter and select "Extended".

6. Save and exit.

If not using the serial, paralell ports or the floppy you can remove from the bios. This will reduce i/o in the VM's as well as reducing the DMA memory allocation.