reserve

Synopsis:

reserve options

Options:

intr number

Prevent the qvm process from allocating the guest interrupt specified by number.

loc location_spec

Prevent the qvm process from allocating the location specified by location_spec. The format of this argument depends on the type of resource that exists in that location:

• mem:region,length The reserved location is a memory area starting at region and lasting for length bytes.
• io:port[,length] The location is an x86 I/O region. The first argument is a port number and this is optionally followed by a length in bytes.
• pci:pci_bus:pci_dev[.pci_func] The location is a PCI location. For reserve loc, you must use the BDF specification form, and you may not specify a length.

For more information about locations, see Guest resource types in the Configuration chapter.

Description:

The reserve option reserves locations in guest-physical memory and/or guest interrupts to prevent the qvm process from allocating them to any component or device.

If a guest OS expects that specific locations will hold some predetermined artifact (such as a table), or that specific interrupts will be used for some predetermined purposes, you should use the reserve option to ensure that when the qvm process assembles the VM for the guest it doesn't inadvertently allocate these locations and interrupts, and leaves them for you to allocate as your guest requires.

The following examples illustrate how this option can be used to reserve different types of resources:

• Guest interrupt 39:

  reserve intr 39

• PCI device 1 on bus 0:

  reserve loc pci:0:1

• An x86 I/O region of eight bytes at 0xcf:

  reserve loc io 0xcf,0x8

• A memory region of eight bytes at 0x1000:

  reserve loc 0x1000,0x8