OvmfPkg/README - device/linaro/bootloader/edk2 - Git at Google


 === OVMF OVERVIEW ===

 The Open Virtual Machine Firmware (OVMF) project aims
 to support firmware for Virtual Machines using the edk2
 code base.  More information can be found at:

 http://www.tianocore.org/ovmf/

 === STATUS ===

 Current capabilities:
 * IA32 and X64 architectures
 * QEMU (0.10.0 or later)
   - Video, keyboard, IDE, CD-ROM, serial
   - Runs UEFI shell
   - Optional NIC support.  Requires QEMU (0.12.2 or later)
 * UEFI Linux boots
 * UEFI Windows 8 boots
 * UEFI Windows 7 & Windows 2008 Server boot (see important notes below!)

 === FUTURE PLANS ===

 * Test/Stabilize UEFI Self-Certification Tests (SCT) results

 === BUILDING OVMF ===

 Pre-requisites:
 * Build environment capable of build the edk2 MdeModulePkg.
 * A properly configured ASL compiler:
   - Intel ASL compiler: Available from http://www.acpica.org
   - Microsoft ASL compiler: Available from http://www.acpi.info
 * NASM: http://www.nasm.us/

 Update Conf/target.txt ACTIVE_PLATFORM for OVMF:
                              PEI arch   DXE arch   UEFI interfaces
 * OvmfPkg/OvmfPkgIa32.dsc      IA32       IA32           IA32
 * OvmfPkg/OvmfPkgIa32X64.dsc   IA32       X64            X64
 * OvmfPkg/OvmfPkgX64.dsc       X64        X64            X64

 Update Conf/target.txt TARGET_ARCH based on the .dsc file:
                              TARGET_ARCH
 * OvmfPkg/OvmfPkgIa32.dsc     IA32
 * OvmfPkg/OvmfPkgIa32X64.dsc  IA32 X64
 * OvmfPkg/OvmfPkgX64.dsc      X64

 Following the edk2 build process, you will find the OVMF binaries
 under the $WORKSPACE/Build/*/*/FV directory.  The actual path will
 depend on how your build is configured.  You can expect to find
 these binary outputs:
 * OVMF.FD
   - Please note!  This filename has changed.  Older releases used OVMF.Fv.
 * OvmfVideo.rom
   - This file is not built separately any longer, starting with svn r13520.

 More information on building OVMF can be found at:

 https://github.com/tianocore/tianocore.github.io/wiki/How%20to%20build%20OVMF

 === RUNNING OVMF on QEMU ===

 * QEMU 0.12.2 or later is required.
 * Be sure to use qemu-system-x86_64, if you are using and X64 firmware.
   (qemu-system-x86_64 works for the IA32 firmware as well, of course.)
 * Use OVMF for QEMU firmware (3 options available)
   - Option 1: QEMU 1.6 or newer; Use QEMU -pflash parameter
     * QEMU/OVMF will use emulated flash, and fully support UEFI variables
     * Run qemu with: -pflash path/to/OVMF.fd
     * Note that this option is required for running SecureBoot-enabled builds
       (-D SECURE_BOOT_ENABLE).
   - Option 2: Use QEMU -bios parameter
     * Note that UEFI variables will be partially emulated, and non-volatile
       variables may lose their contents after a reboot
     * Run qemu with: -bios path/to/OVMF.fd
   - Option 3: Use QEMU -L parameter
     * Note that UEFI variables will be partially emulated, and non-volatile
       variables may lose their contents after a reboot
     * Either copy, rename or symlink OVMF.fd => bios.bin
     * Use the QEMU -L parameter to specify the directory where the bios.bin
       file is located.
 * The EFI shell is built into OVMF builds at this time, so it should
   run automatically if a UEFI boot application is not found on the
   removable media.
 * On Linux, newer version of QEMU may enable KVM feature, and this might
   cause OVMF to fail to boot.  The QEMU '-no-kvm' may allow OVMF to boot.
 * Capturing OVMF debug messages on qemu:
   - The default OVMF build writes debug messages to IO port 0x402.  The
     following qemu command line options save them in the file called
     debug.log: '-debugcon file:debug.log -global isa-debugcon.iobase=0x402'.
   - It is possible to revert to the original behavior, when debug messages were
     written to the emulated serial port (potentially intermixing OVMF debug
     output with UEFI serial console output).  For this the
     '-D DEBUG_ON_SERIAL_PORT' option has to be passed to the build command (see
     the next section), and in order to capture the serial output qemu needs to
     be started with eg. '-serial file:serial.log'.
   - Debug messages fall into several categories.  Logged vs. suppressed
     categories are controlled at OVMF build time by the
     'gEfiMdePkgTokenSpaceGuid.PcdDebugPrintErrorLevel' bitmask (an UINT32
     value) in the selected .dsc file.  Individual bits of this bitmask are
     defined in <MdePkg/Include/Library/DebugLib.h>.  One non-default bit (with
     some performance impact) that is frequently set for debugging is 0x00400000
     (DEBUG_VERBOSE).
   - The RELEASE build target ('-b RELEASE' build option, see below) disables
     all debug messages.  The default build target is DEBUG.

 === Build Scripts ===

 On systems with the bash shell you can use OvmfPkg/build.sh to simplify
 building and running OVMF.

 So, for example, to build + run OVMF X64:
 $ OvmfPkg/build.sh -a X64
 $ OvmfPkg/build.sh -a X64 qemu

 And to run a 64-bit UEFI bootable ISO image:
 $ OvmfPkg/build.sh -a X64 qemu -cdrom /path/to/disk-image.iso

 To build a 32-bit OVMF without debug messages using GCC 4.5:
 $ OvmfPkg/build.sh -a IA32 -b RELEASE -t GCC45

 === SMM support ===

 Requirements:
 * SMM support requires QEMU 2.5.
 * The minimum required QEMU machine type is "pc-q35-2.5".
 * SMM with KVM requires Linux 4.4 (host).

 OVMF is capable of utilizing SMM if the underlying QEMU or KVM hypervisor
 emulates SMM. SMM is put to use in the S3 suspend and resume infrastructure,
 and in the UEFI variable driver stack. The purpose is (virtual) hardware
 separation between the runtime guest OS and the firmware (OVMF), with the
 intent to make Secure Boot actually secure, by preventing the runtime guest OS
 from tampering with the variable store and S3 areas.

 For SMM support, OVMF must be built with the "-D SMM_REQUIRE" option. The
 resultant firmware binary will check if QEMU actually provides SMM emulation;
 if it doesn't, then OVMF will log an error and trigger an assertion failure
 during boot (even in RELEASE builds). Both the naming of the flag (SMM_REQUIRE,
 instead of SMM_ENABLE), and this behavior are consistent with the goal
 described above: this is supposed to be a security feature, and fallbacks are
 not allowed. Similarly, a pflash-backed variable store is a requirement.

 QEMU should be started with the options listed below (in addition to any other
 guest-specific flags). The command line should be gradually composed from the
 hints below. '\' is used to extend the command line to multiple lines, and '^'
 can be used on Windows.

 * QEMU binary and options specific to 32-bit guests:

   $ qemu-system-i386 -cpu coreduo,-nx \

   or

   $ qemu-system-x86_64 -cpu <MODEL>,-lm,-nx \

 * QEMU binary for running 64-bit guests (no particular options):

   $ qemu-system-x86_64 \

 * Flags common to all SMM scenarios (only the Q35 machine type is supported):

   -machine q35,smm=on,accel=(tcg|kvm) \
   -m ... \
   -smp ... \
   -global driver=cfi.pflash01,property=secure,value=on \
   -drive if=pflash,format=raw,unit=0,file=OVMF_CODE.fd,readonly=on \
   -drive if=pflash,format=raw,unit=1,file=copy_of_OVMF_VARS.fd \

 * In order to disable S3, add:

   -global ICH9-LPC.disable_s3=1 \

 === Network Support ===

 OVMF provides a UEFI network stack by default. Its lowest level driver is the
 NIC driver, higher levels are generic. In order to make DHCP, PXE Boot, and eg.
 socket test utilities from the StdLib edk2 package work, (1) qemu has to be
 configured to emulate a NIC, (2) a matching UEFI NIC driver must be available
 when OVMF boots.

 (If a NIC is configured for the virtual machine, and -- dependent on boot order
 -- PXE booting is attempted, but no DHCP server responds to OVMF's DHCP
 DISCOVER message at startup, the boot process may take approx. 3 seconds
 longer.)

 * For each NIC emulated by qemu, a GPLv2 licensed UEFI driver is available from
   the iPXE project. The qemu source distribution, starting with version 1.5,
   contains prebuilt binaries of these drivers (and of course allows one to
   rebuild them from source as well). This is the recommended set of drivers.

 * Use the qemu -netdev and -device options, or the legacy -net option, to
   enable NIC support: <http://wiki.qemu.org/Documentation/Networking>.

 * For a qemu >= 1.5 binary running *without* any "-M machine" option where
   "machine" would identify a < qemu-1.5 configuration (for example: "-M
   pc-i440fx-1.4" or "-M pc-0.13"), the iPXE drivers are automatically available
   to and configured for OVMF in the default qemu installation.

 * For a qemu binary in [0.13, 1.5), or a qemu >= 1.5 binary with an "-M
   machine" option where "machine" selects a < qemu-1.5 configuration:

   - download a >= 1.5.0-rc1 source tarball from <http://wiki.qemu.org/Download>,

   - extract the following iPXE driver files from the tarball and install them
     in a location that is accessible to qemu processes (this may depend on your
     SELinux configuration, for example):

     qemu-VERSION/pc-bios/efi-e1000.rom
     qemu-VERSION/pc-bios/efi-ne2k_pci.rom
     qemu-VERSION/pc-bios/efi-pcnet.rom
     qemu-VERSION/pc-bios/efi-rtl8139.rom
     qemu-VERSION/pc-bios/efi-virtio.rom

   - extend the NIC's -device option on the qemu command line with a matching
     "romfile=" optarg:

     -device e1000,...,romfile=/full/path/to/efi-e1000.rom
     -device ne2k_pci,...,romfile=/full/path/to/efi-ne2k_pci.rom
     -device pcnet,...,romfile=/full/path/to/efi-pcnet.rom
     -device rtl8139,...,romfile=/full/path/to/efi-rtl8139.rom
     -device virtio-net-pci,...,romfile=/full/path/to/efi-virtio.rom

 * Independently of the iPXE NIC drivers, the default OVMF build provides a
   basic virtio-net driver, located in OvmfPkg/VirtioNetDxe.

 * Also independently of the iPXE NIC drivers, Intel's proprietary E1000 NIC
   driver (PROEFI) can be embedded in the OVMF image at build time:

   - Download UEFI drivers for the e1000 NIC
     - http://downloadcenter.intel.com/Detail_Desc.aspx?agr=Y&DwnldID=17515&lang=eng
     - Install the drivers into a directory called Intel3.5 in your WORKSPACE.

   - Include the driver in OVMF during the build:
     - Add "-D E1000_ENABLE" to your build command,
     - For example: "build -D E1000_ENABLE".

 * When a matching iPXE driver is configured for a NIC as described above, it
   takes priority over other drivers that could possibly drive the card too:

                  | e1000  ne2k_pci  pcnet  rtl8139  virtio-net-pci
     -------------+------------------------------------------------
     iPXE         |   x       x        x       x           x
     VirtioNetDxe |                                        x
     Intel PROEFI |   x

 === OVMF Flash Layout ===

 Like all current IA32/X64 system designs, OVMF's firmware
 device (rom/flash) appears in QEMU's physical address space
 just below 4GB (0x100000000).

 The layout of the firmware device in memory looks like:

 +--------------------------------------- 4GB (0x100000000)
 | VTF0 (16-bit reset code) and OVMF SEC
 | (SECFV)
 +--------------------------------------- varies based on flash size
 |
 | Compressed main firmware image
 | (FVMAIN_COMPACT)
 |
 +--------------------------------------- base + 0x20000
 | Fault-tolerant write (FTW)
 | Spare blocks (64KB/0x10000)
 +--------------------------------------- base + 0x10000
 | FTW Work block (4KB/0x1000)
 +--------------------------------------- base + 0x0f000
 | Event log area (4KB/0x1000)
 +--------------------------------------- base + 0x0e000
 | Non-volatile variable storage
 | area (56KB/0xe000)
 +--------------------------------------- base address

 OVMF supports building a 1MB or a 2MB flash image. The base address for
 a 1MB image in QEMU physical memory is 0xfff00000. The base address for
 a 2MB image is 0xffe00000.

 The code in SECFV locates FVMAIN_COMPACT, and decompresses the
 main firmware (MAINFV) into RAM memory at address 0x800000. The
 remaining OVMF firmware then uses this decompressed firmware
 volume image.

 === UNIXGCC Debug ===

 If you build with the UNIXGCC toolchain, then debugging will be disabled
 due to larger image sizes being produced by the UNIXGCC toolchain. The
 first choice recommendation is to use GCC44 or newer instead.

 If you must use UNIXGCC, then you can override the build options for
 particular libraries and modules in the .dsc to re-enable debugging
 selectively. For example:
   [Components]
   OvmfPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf {
     <BuildOptions>
       GCC:*_*_*_CC_FLAGS             = -UMDEPKG_NDEBUG
   }
   MdeModulePkg/Universal/BdsDxe/BdsDxe.inf {
     <BuildOptions>
       GCC:*_*_*_CC_FLAGS             = -UMDEPKG_NDEBUG
   }

 === UEFI Windows 7 & Windows 2008 Server ===

 * One of the '-vga std' and '-vga qxl' QEMU options should be used.
 * Only one video mode, 1024x768x32, is supported at OS runtime.
 * The '-vga qxl' QEMU option is recommended. After booting the installed
   guest OS, select the video card in Device Manager, and upgrade its driver
   to the QXL XDDM one. Download location:
   <http://www.spice-space.org/download.html>, Guest | Windows binaries.
   This enables further resolutions at OS runtime, and provides S3
   (suspend/resume) capability.

	=== OVMF OVERVIEW ===

	The Open Virtual Machine Firmware (OVMF) project aims
	to support firmware for Virtual Machines using the edk2
	code base. More information can be found at:

	http://www.tianocore.org/ovmf/

	=== STATUS ===

	Current capabilities:
	* IA32 and X64 architectures
	* QEMU (0.10.0 or later)
	- Video, keyboard, IDE, CD-ROM, serial
	- Runs UEFI shell
	- Optional NIC support. Requires QEMU (0.12.2 or later)
	* UEFI Linux boots
	* UEFI Windows 8 boots
	* UEFI Windows 7 & Windows 2008 Server boot (see important notes below!)

	=== FUTURE PLANS ===

	* Test/Stabilize UEFI Self-Certification Tests (SCT) results

	=== BUILDING OVMF ===

	Pre-requisites:
	* Build environment capable of build the edk2 MdeModulePkg.
	* A properly configured ASL compiler:
	- Intel ASL compiler: Available from http://www.acpica.org
	- Microsoft ASL compiler: Available from http://www.acpi.info
	* NASM: http://www.nasm.us/

	Update Conf/target.txt ACTIVE_PLATFORM for OVMF:
	PEI arch DXE arch UEFI interfaces
	* OvmfPkg/OvmfPkgIa32.dsc IA32 IA32 IA32
	* OvmfPkg/OvmfPkgIa32X64.dsc IA32 X64 X64
	* OvmfPkg/OvmfPkgX64.dsc X64 X64 X64

	Update Conf/target.txt TARGET_ARCH based on the .dsc file:
	TARGET_ARCH
	* OvmfPkg/OvmfPkgIa32.dsc IA32
	* OvmfPkg/OvmfPkgIa32X64.dsc IA32 X64
	* OvmfPkg/OvmfPkgX64.dsc X64

	Following the edk2 build process, you will find the OVMF binaries
	under the $WORKSPACE/Build///FV directory. The actual path will
	depend on how your build is configured. You can expect to find
	these binary outputs:
	* OVMF.FD
	- Please note! This filename has changed. Older releases used OVMF.Fv.
	* OvmfVideo.rom
	- This file is not built separately any longer, starting with svn r13520.

	More information on building OVMF can be found at:

	https://github.com/tianocore/tianocore.github.io/wiki/How%20to%20build%20OVMF

	=== RUNNING OVMF on QEMU ===

	* QEMU 0.12.2 or later is required.
	* Be sure to use qemu-system-x86_64, if you are using and X64 firmware.
	(qemu-system-x86_64 works for the IA32 firmware as well, of course.)
	* Use OVMF for QEMU firmware (3 options available)
	- Option 1: QEMU 1.6 or newer; Use QEMU -pflash parameter
	* QEMU/OVMF will use emulated flash, and fully support UEFI variables
	* Run qemu with: -pflash path/to/OVMF.fd
	* Note that this option is required for running SecureBoot-enabled builds
	(-D SECURE_BOOT_ENABLE).
	- Option 2: Use QEMU -bios parameter
	* Note that UEFI variables will be partially emulated, and non-volatile
	variables may lose their contents after a reboot
	* Run qemu with: -bios path/to/OVMF.fd
	- Option 3: Use QEMU -L parameter
	* Note that UEFI variables will be partially emulated, and non-volatile
	variables may lose their contents after a reboot
	* Either copy, rename or symlink OVMF.fd => bios.bin
	* Use the QEMU -L parameter to specify the directory where the bios.bin
	file is located.
	* The EFI shell is built into OVMF builds at this time, so it should
	run automatically if a UEFI boot application is not found on the
	removable media.
	* On Linux, newer version of QEMU may enable KVM feature, and this might
	cause OVMF to fail to boot. The QEMU '-no-kvm' may allow OVMF to boot.
	* Capturing OVMF debug messages on qemu:
	- The default OVMF build writes debug messages to IO port 0x402. The
	following qemu command line options save them in the file called
	debug.log: '-debugcon file:debug.log -global isa-debugcon.iobase=0x402'.
	- It is possible to revert to the original behavior, when debug messages were
	written to the emulated serial port (potentially intermixing OVMF debug
	output with UEFI serial console output). For this the
	'-D DEBUG_ON_SERIAL_PORT' option has to be passed to the build command (see
	the next section), and in order to capture the serial output qemu needs to
	be started with eg. '-serial file:serial.log'.
	- Debug messages fall into several categories. Logged vs. suppressed
	categories are controlled at OVMF build time by the
	'gEfiMdePkgTokenSpaceGuid.PcdDebugPrintErrorLevel' bitmask (an UINT32
	value) in the selected .dsc file. Individual bits of this bitmask are
	defined in <MdePkg/Include/Library/DebugLib.h>. One non-default bit (with
	some performance impact) that is frequently set for debugging is 0x00400000
	(DEBUG_VERBOSE).
	- The RELEASE build target ('-b RELEASE' build option, see below) disables
	all debug messages. The default build target is DEBUG.

	=== Build Scripts ===

	On systems with the bash shell you can use OvmfPkg/build.sh to simplify
	building and running OVMF.

	So, for example, to build + run OVMF X64:
	$ OvmfPkg/build.sh -a X64
	$ OvmfPkg/build.sh -a X64 qemu

	And to run a 64-bit UEFI bootable ISO image:
	$ OvmfPkg/build.sh -a X64 qemu -cdrom /path/to/disk-image.iso

	To build a 32-bit OVMF without debug messages using GCC 4.5:
	$ OvmfPkg/build.sh -a IA32 -b RELEASE -t GCC45

	=== SMM support ===

	Requirements:
	* SMM support requires QEMU 2.5.
	* The minimum required QEMU machine type is "pc-q35-2.5".
	* SMM with KVM requires Linux 4.4 (host).

	OVMF is capable of utilizing SMM if the underlying QEMU or KVM hypervisor
	emulates SMM. SMM is put to use in the S3 suspend and resume infrastructure,
	and in the UEFI variable driver stack. The purpose is (virtual) hardware
	separation between the runtime guest OS and the firmware (OVMF), with the
	intent to make Secure Boot actually secure, by preventing the runtime guest OS
	from tampering with the variable store and S3 areas.

	For SMM support, OVMF must be built with the "-D SMM_REQUIRE" option. The
	resultant firmware binary will check if QEMU actually provides SMM emulation;
	if it doesn't, then OVMF will log an error and trigger an assertion failure
	during boot (even in RELEASE builds). Both the naming of the flag (SMM_REQUIRE,
	instead of SMM_ENABLE), and this behavior are consistent with the goal
	described above: this is supposed to be a security feature, and fallbacks are
	not allowed. Similarly, a pflash-backed variable store is a requirement.

	QEMU should be started with the options listed below (in addition to any other
	guest-specific flags). The command line should be gradually composed from the
	hints below. '\' is used to extend the command line to multiple lines, and '^'
	can be used on Windows.

	* QEMU binary and options specific to 32-bit guests:

	$ qemu-system-i386 -cpu coreduo,-nx \

	or

	$ qemu-system-x86_64 -cpu <MODEL>,-lm,-nx \

	* QEMU binary for running 64-bit guests (no particular options):

	$ qemu-system-x86_64 \

	* Flags common to all SMM scenarios (only the Q35 machine type is supported):

	-machine q35,smm=on,accel=(tcg\|kvm) \
	-m ... \
	-smp ... \
	-global driver=cfi.pflash01,property=secure,value=on \
	-drive if=pflash,format=raw,unit=0,file=OVMF_CODE.fd,readonly=on \
	-drive if=pflash,format=raw,unit=1,file=copy_of_OVMF_VARS.fd \

	* In order to disable S3, add:

	-global ICH9-LPC.disable_s3=1 \

	=== Network Support ===

	OVMF provides a UEFI network stack by default. Its lowest level driver is the
	NIC driver, higher levels are generic. In order to make DHCP, PXE Boot, and eg.
	socket test utilities from the StdLib edk2 package work, (1) qemu has to be
	configured to emulate a NIC, (2) a matching UEFI NIC driver must be available
	when OVMF boots.

	(If a NIC is configured for the virtual machine, and -- dependent on boot order
	-- PXE booting is attempted, but no DHCP server responds to OVMF's DHCP
	DISCOVER message at startup, the boot process may take approx. 3 seconds
	longer.)

	* For each NIC emulated by qemu, a GPLv2 licensed UEFI driver is available from
	the iPXE project. The qemu source distribution, starting with version 1.5,
	contains prebuilt binaries of these drivers (and of course allows one to
	rebuild them from source as well). This is the recommended set of drivers.

	* Use the qemu -netdev and -device options, or the legacy -net option, to
	enable NIC support: <http://wiki.qemu.org/Documentation/Networking>.

	* For a qemu >= 1.5 binary running without any "-M machine" option where
	"machine" would identify a < qemu-1.5 configuration (for example: "-M
	pc-i440fx-1.4" or "-M pc-0.13"), the iPXE drivers are automatically available
	to and configured for OVMF in the default qemu installation.

	* For a qemu binary in [0.13, 1.5), or a qemu >= 1.5 binary with an "-M
	machine" option where "machine" selects a < qemu-1.5 configuration:

	- download a >= 1.5.0-rc1 source tarball from <http://wiki.qemu.org/Download>,

	- extract the following iPXE driver files from the tarball and install them
	in a location that is accessible to qemu processes (this may depend on your
	SELinux configuration, for example):

	qemu-VERSION/pc-bios/efi-e1000.rom
	qemu-VERSION/pc-bios/efi-ne2k_pci.rom
	qemu-VERSION/pc-bios/efi-pcnet.rom
	qemu-VERSION/pc-bios/efi-rtl8139.rom
	qemu-VERSION/pc-bios/efi-virtio.rom

	- extend the NIC's -device option on the qemu command line with a matching
	"romfile=" optarg:

	-device e1000,...,romfile=/full/path/to/efi-e1000.rom
	-device ne2k_pci,...,romfile=/full/path/to/efi-ne2k_pci.rom
	-device pcnet,...,romfile=/full/path/to/efi-pcnet.rom
	-device rtl8139,...,romfile=/full/path/to/efi-rtl8139.rom
	-device virtio-net-pci,...,romfile=/full/path/to/efi-virtio.rom

	* Independently of the iPXE NIC drivers, the default OVMF build provides a
	basic virtio-net driver, located in OvmfPkg/VirtioNetDxe.

	* Also independently of the iPXE NIC drivers, Intel's proprietary E1000 NIC
	driver (PROEFI) can be embedded in the OVMF image at build time:

	- Download UEFI drivers for the e1000 NIC
	- http://downloadcenter.intel.com/Detail_Desc.aspx?agr=Y&DwnldID=17515&lang=eng
	- Install the drivers into a directory called Intel3.5 in your WORKSPACE.

	- Include the driver in OVMF during the build:
	- Add "-D E1000_ENABLE" to your build command,
	- For example: "build -D E1000_ENABLE".

	* When a matching iPXE driver is configured for a NIC as described above, it
	takes priority over other drivers that could possibly drive the card too:

	\| e1000 ne2k_pci pcnet rtl8139 virtio-net-pci
	-------------+------------------------------------------------
	iPXE \| x x x x x
	VirtioNetDxe \| x
	Intel PROEFI \| x

	=== OVMF Flash Layout ===

	Like all current IA32/X64 system designs, OVMF's firmware
	device (rom/flash) appears in QEMU's physical address space
	just below 4GB (0x100000000).

	The layout of the firmware device in memory looks like:

	+--------------------------------------- 4GB (0x100000000)
	\| VTF0 (16-bit reset code) and OVMF SEC
	\| (SECFV)
	+--------------------------------------- varies based on flash size
	\|
	\| Compressed main firmware image
	\| (FVMAIN_COMPACT)
	\|
	+--------------------------------------- base + 0x20000
	\| Fault-tolerant write (FTW)
	\| Spare blocks (64KB/0x10000)
	+--------------------------------------- base + 0x10000
	\| FTW Work block (4KB/0x1000)
	+--------------------------------------- base + 0x0f000
	\| Event log area (4KB/0x1000)
	+--------------------------------------- base + 0x0e000
	\| Non-volatile variable storage
	\| area (56KB/0xe000)
	+--------------------------------------- base address

	OVMF supports building a 1MB or a 2MB flash image. The base address for
	a 1MB image in QEMU physical memory is 0xfff00000. The base address for
	a 2MB image is 0xffe00000.

	The code in SECFV locates FVMAIN_COMPACT, and decompresses the
	main firmware (MAINFV) into RAM memory at address 0x800000. The
	remaining OVMF firmware then uses this decompressed firmware
	volume image.

	=== UNIXGCC Debug ===

	If you build with the UNIXGCC toolchain, then debugging will be disabled
	due to larger image sizes being produced by the UNIXGCC toolchain. The
	first choice recommendation is to use GCC44 or newer instead.

	If you must use UNIXGCC, then you can override the build options for
	particular libraries and modules in the .dsc to re-enable debugging
	selectively. For example:
	[Components]
	OvmfPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf {
	<BuildOptions>
	GCC:__*_CC_FLAGS = -UMDEPKG_NDEBUG
	}
	MdeModulePkg/Universal/BdsDxe/BdsDxe.inf {
	<BuildOptions>
	GCC:__*_CC_FLAGS = -UMDEPKG_NDEBUG
	}

	=== UEFI Windows 7 & Windows 2008 Server ===

	* One of the '-vga std' and '-vga qxl' QEMU options should be used.
	* Only one video mode, 1024x768x32, is supported at OS runtime.
	* The '-vga qxl' QEMU option is recommended. After booting the installed
	guest OS, select the video card in Device Manager, and upgrade its driver
	to the QXL XDDM one. Download location:
	<http://www.spice-space.org/download.html>, Guest \| Windows binaries.
	This enables further resolutions at OS runtime, and provides S3
	(suspend/resume) capability.