From 57bb28ef9522a8740fe8923865646110edf6392f Mon Sep 17 00:00:00 2001 From: Fiona Ebner Date: Tue, 20 Jun 2023 09:25:25 +0200 Subject: [PATCH] qm: fix typos and improve wording in CPU Types section Signed-off-by: Fiona Ebner --- qm.adoc | 33 ++++++++++++++++++--------------- 1 file changed, 18 insertions(+), 15 deletions(-) diff --git a/qm.adoc b/qm.adoc index 33b1986..0fbc30a 100644 --- a/qm.adoc +++ b/qm.adoc @@ -352,9 +352,9 @@ CPU Type QEMU can emulate a number different of *CPU types* from 486 to the latest Xeon processors. Each new processor generation adds new features, like hardware -assisted 3d rendering, random number generation, memory protection, etc ... -Also, a current generation can be upgraded through microcode update with bugs -or security fixes. +assisted 3d rendering, random number generation, memory protection, etc.. Also, +a current generation can be upgraded through microcode update with bug or +security fixes. Usually you should select for your VM a processor type which closely matches the CPU of the host system, as it means that the host CPU features (also called _CPU @@ -364,25 +364,28 @@ as your host system. This has a downside though. If you want to do a live migration of VMs between different hosts, your VM might end up on a new system with a different CPU type -or a different microcode. -If the CPU flags passed to the guest are missing, the qemu process will stop. To -remedy this QEMU has also its own virtual CPU types, that {pve} uses by defaults. +or a different microcode version. +If the CPU flags passed to the guest are missing, the QEMU process will stop. To +remedy this QEMU has also its own virtual CPU types, that {pve} uses by default. -Default is x86-64-v2-AES, compatible with Intel >= Westmere and Amd >= Opteron_G4 +The backend default is 'kvm64' which works on essentially all x86_64 host CPUs +and the UI default when creating a new VM is 'x86-64-v2-AES', which requires a +host CPU starting from Westmere for Intel or at least a fourth generation +Opteron for AMD. In short: -If you don’t care about live migration or have a homogeneous cluster where -all nodes have the same CPU and same microcode version, set the CPU type to host, as in -theory this will give your guests maximum performance. +If you don’t care about live migration or have a homogeneous cluster where all +nodes have the same CPU and same microcode version, set the CPU type to host, as +in theory this will give your guests maximum performance. -if you care about live migration and security, and you have only Intel CPU or only AMD CPU, -choose the lowest generation cpu model of your cluster. +If you care about live migration and security, and you have only Intel CPUs or +only AMD CPUs, choose the lowest generation CPU model of your cluster. -if you care about live migration without security, or have mixed intel/amd cluster, -choose the lowest compatible virtual qemu type. +If you care about live migration without security, or have mixed Intel/AMD +cluster, choose the lowest compatible virtual QEMU CPU type. -NOTE: Intel <> AMD migrations have no guarantee to work +NOTE: Live migrations between Intel and AMD host CPUs have no guarantee to work. Intel CPU Types since 2007 -- 2.39.2