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Virtualized Hardware

Red Hat Enterprise Virtualization presents three distinct types of system devices to virtualized guests. These hardware devices all appear as physically attached hardware devices to the virtualized guest but the device drivers work in different ways.
Emulated devices
Emulated devices, sometimes referred to as virtual devices, exist entirely in software. Emulated device drivers are a translation layer between the operating system running on the host (which manages the source device) and the operating systems running on the guests. The device level instructions directed to and from the emulated device are intercepted and translated by the hypervisor. Any device of the same type as that being emulated and recognized by the Linux kernel is able to be used as the backing source device for the emulated drivers.
Para-virtualized Devices
Para-virtualized devices require the installation of device drivers on the guest operating system providing it with an interface to communicate with the hypervisor on the host machine. This interface is used to allow traditionally intensive tasks such as disk I/O to be performed outside of the virtualized environment. Lowering the overhead inherent in virtualization in this manner is intended to allow guest operating system performance closer to that expected when running directly on physical hardware.
Physically shared devices
Certain hardware platforms allow virtualized guests to directly access various hardware devices and components. This process in virtualization is known as passthrough or device assignment. Passthrough allows devices to appear and behave as if they were physically attached to the guest operating system.

C.1. Central Processing Unit (CPU)

Each Red Hat Enterprise Virtualization Hypervisor within a Cluster has a number of virtual CPUs (vCPUS). The virtual CPUs are in turn exposed to guests running on the hypervisors. All virtual CPUs exposed by Hypervisors within a Cluster are of the type selected when the Cluster was initially created via Red Hat Enterprise Virtualization Manager. Mixing of virtual CPU types within a Cluster is not possible.
Each available virtual CPU type has characteristics based on physical CPUs of the same name. The virtual CPU is indistinguishable from the physical CPU to the guest operating system.
AMD Opteron G1.
See Table C.1, “AMD Opteron G1” for specifications.
AMD Opteron G2
See Table C.2, “AMD Opteron G2” for specifications.
AMD Opteron G3
See Table C.3, “AMD Opteron G3” for specifications.
Intel Xeon Core 2
See Table C.4, “Intel Xeon Core2” for specifications.
Intel Xeon 45nm Core2
See Table C.5, “Intel Xeon 45nm Core2” for specifications.
Intel Xeon Core i7
See Table C.6, “Intel Xeon Core i7” for specifications.

Note — Support for x2APIC

All virtual CPU models provided by Red Hat Enterprise Linux 6 hosts include support for x2APIC. This provides an Advanced Programmable Interrupt Controller (APIC) to better handle hardware interrupts.

C.1.1. CPU Specifications

The reference tables provided in this section detail the specifications of the virtual CPUs which Red Hat Enterprise Virtualization is able to expose to guests.
Table C.1. AMD Opteron G1
Field
Value
model
Opteron_G1 AMD Opteron 240 (Gen 1 Class Opteron)
family
15
model
6
stepping
1
level
5
xlevel
0x80000008
vendor
AuthenticAMD
feature_edx
sse2 sse fxsr mmx clflush pse36 pat cmov mca pge mtrr sep apic cx8 mce pae msr tsc pse de fpu
feature_ecx
x2apic pni|sse3
extfeature_edx
lm fxsr mmx nx pat cmov pge syscall apic cx8 mce pae msr tsc pse de fpu
extfeature_ecx

Table C.2. AMD Opteron G2
Field
Value
model
Opteron_G2 AMD Opteron 22xx (Gen 2 Class Opteron)
family
15
model
6
stepping
1
level
5
xlevel
0x80000008
vendor
AuthenticAMD
feature_edx
sse2 sse fxsr mmx clflush pse36 pat cmov mca pge mtrr sep apic cx8 mce pae msr tsc pse de fpu
feature_ecx
x2apic cx16 pni|sse3
extfeature_edx
lm rdtscp fxsr mmx nx pat cmov pge syscall apic cx8 mce pae msr tsc pse de fpu
extfeature_ecx
svm lahf_lm

Table C.3. AMD Opteron G3
Field
Value
model
Opteron_G3 AMD Opteron 23xx (Gen 3 Class Opteron)
family
15
model
6
stepping
1
level
5
xlevel
0x80000008
vendor
AuthenticAMD
feature_edx
sse2 sse fxsr mmx clflush pse36 pat cmov mca pge mtrr sep apic cx8 mce pae msr tsc pse de fpu
feature_ecx
popcnt x2apic cx16 monitor pni|sse3
extfeature_edx
lm rdtscp fxsr mmx nx pat cmov pge syscall apic cx8 mce pae msr tsc pse de fpu
extfeature_ecx
misalignsse sse4a abm svm lahf_lm

Table C.4. Intel Xeon Core2
Field
Value
model
Conroe Intel Celeron_4x0 (Conroe/Merom Class Core 2)
family
6
model
15
stepping
3
level
2
xlevel
0x8000000a
vendor
GenuineIntel
feature_edx
sse2 sse fxsr mmx clflush pse36 pat cmov mca pge mtrr sep apic cx8 mce pae msr tsc pse de fpu
feature_ecx
x2apic ssse3 pni|sse3
extfeature_edx
lm fxsr mmx nx pat cmov pge syscall apic cx8 mce pae msr tsc pse de fpu
extfeature_ecx
lahf_lm

Table C.5. Intel Xeon 45nm Core2
Field
Value
model
Penryn Intel Core 2 Duo P9xxx (Penryn Class Core 2)
family
6
model
23
stepping
3
level
2
xlevel
0x8000000a
vendor
GenuineIntel
feature_edx
sse2 sse fxsr mmx clflush pse36 pat cmov mca pge mtrr sep apic cx8 mce pae msr tsc pse de fpu
feature_ecx
x2apic sse4.1|sse4_1 cx16 ssse3 pni|sse3
extfeature_edx
lm fxsr mmx nx pat cmov pge syscall apic cx8 mce pae msr tsc pse de fpu
extfeature_ecx
lahf_lm

Table C.6. Intel Xeon Core i7
Field
Value
model
Nehalem Intel Core i7 9xx (Nehalem Class Core i7)
family
6
model
26
stepping
3
level
2
xlevel
0x8000000a
vendor
GenuineIntel
feature_edx
sse2 sse fxsr mmx clflush pse36 pat cmov mca pge mtrr sep apic cx8 mce pae msr tsc pse de fpu
feature_ecx
popcnt x2apic sse4.2|sse4_2 sse4.1|sse4_1 cx16 ssse3 pni|sse3
extfeature_edx
lm fxsr mmx nx pat cmov pge syscall apic cx8 mce pae msr tsc pse de fpu
extfeature_ecx
lahf_lm