Oracle Audio Technologies E10898-02 - Manual (Page 102)

Hardware Virtualized Guest Stops
E-6 Oracle VM Server User's Guide
Restart Oracle VM Server for the changes to take effect.
E.9 Hardware Virtualized Guest Stops
When running hardware virtualized guests, the QEMU process (qemu-dm) may have
its memory usage grow substantially, especially under heavy I/O loads. This may
cause the hardware virtualized guest to stop as it runs out of memory. If the guest is
stopped, increase the memory allocation for dom0, for example from 512MB to 768MB.
E.10 Hardware Virtualized Guest Devices Not Working as Expected
Some devices, such as sound cards, may not work as expected in hardware virtualized
guests. In a hardware virtualized guest, a device that requires physical memory
addresses instead uses virtualized memory addresses, so incorrect memory location
values may be set. This is because DMA (Direct Memory Access) is virtualized in
hardware virtualized guests.
Hardware virtualized guest operating systems expect to be loaded in memory starting
somewhere around address 0 and upwards. This is only possible for the first hardware
virtualized guest loaded. Oracle VM Server virtualizes the memory address to be 0 to
the size of allocated memory, but the guest operating system is actually loaded at
another memory location. The difference is fixed up in the shadow page table, but the
operating system is unaware of this.
For example, a sound is loaded into memory in a hardware virtualized guest running
Windows at an address of 100MB may produce garbage through the sound card,
instead of the intended audio. This is because the sound is actually loaded at 100MB
plus 256MB. The sound card receives the address of 100MB, but it is actually at 256MB.
An IOMMU (Input/Output Memory Management Unit) in the computer’s memory
management unit would remove this problem as it would take care of mapping virtual
addresses to physical addresses, and enable hardware virtualized guests direct access
to the hardware.
E.11 Hardware Virtualized Guest Windows Installation
During the installation of Microsoft Windows™ XP and Microsoft Windows™ 2003 as
hardware virtualized guests, the domain requires a restart and attempts to find the
installation CDROM. Oracle VM Server does not know how to find the CDROM. To
workaround this problem:
1. During the domain restart, press F6 or F5 to select a new HAL (Hardware
Abstraction Layer).
2. Select Standard PC and add the CDROM to your guest configuration file, for
example, add the following the /etc/xen/myWindowsGuest file:
disk = [ 'file:/ovm/guests/win2003sp1.dsk,hda,w','file:/ovm/trees/ISO/WIN/en_
windows_server_2003_with_sp1_standard.iso,hdc:cdrom,r', ]
cdrom="/ovm/trees/ISO/WIN/en_windows_server_2003_with_sp1_standard.iso"
3. Restart the hardware virtualized guest with the xm create command. The
installation continues.