[PATCH] docs/s390: clarify even more that cpu-topology is KVM-only

[PATCH] docs/s390: clarify even more that cpu-topology is KVM-only

[Claudio Fontana]

At least for now cpu-topology is implemented only for KVM.

We already say this, but this tries to be more explicit,
and also show it in the examples.

This adds a new reference in the introduction that we can point to,
whenever we need to reference accelerators and how to select them.

Signed-off-by: Claudio Fontana <cfontana@suse.de>
---
 docs/system/introduction.rst       |  2 ++
 docs/system/s390x/cpu-topology.rst | 14 ++++++++------
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/docs/system/introduction.rst b/docs/system/introduction.rst
index 51ac132d6c..746707eb00 100644
--- a/docs/system/introduction.rst
+++ b/docs/system/introduction.rst
@@ -1,6 +1,8 @@
 Introduction
 ============
 
+.. _Accelerators:
+
 Virtualisation Accelerators
 ---------------------------
 
diff --git a/docs/system/s390x/cpu-topology.rst b/docs/system/s390x/cpu-topology.rst
index 5133fdc362..ca344e273c 100644
--- a/docs/system/s390x/cpu-topology.rst
+++ b/docs/system/s390x/cpu-topology.rst
@@ -25,17 +25,19 @@ monitor polarization changes, see ``docs/devel/s390-cpu-topology.rst``.
 Prerequisites
 -------------
 
-To use the CPU topology, you need to run with KVM on a s390x host that
-uses the Linux kernel v6.0 or newer (which provide the so-called
+To use the CPU topology, you currently need to choose the KVM accelerator.
+See :ref:`Accelerators` for more details about accelerators and how to select them.
+
+The s390x host needs to use a Linux kernel v6.0 or newer (which provides the so-called
 ``KVM_CAP_S390_CPU_TOPOLOGY`` capability that allows QEMU to signal the
 CPU topology facility via the so-called STFLE bit 11 to the VM).
 
 Enabling CPU topology
 ---------------------
 
-Currently, CPU topology is only enabled in the host model by default.
+Currently, CPU topology is enabled by default only in the "host" cpu model.
 
-Enabling CPU topology in a CPU model is done by setting the CPU flag
+Enabling CPU topology in another CPU model is done by setting the CPU flag
 ``ctop`` to ``on`` as in:
 
 .. code-block:: bash
@@ -132,7 +134,7 @@ In the following machine we define 8 sockets with 4 cores each.
 
 .. code-block:: bash
 
-  $ qemu-system-s390x -m 2G \
+  $ qemu-system-s390x -accel kvm -m 2G \
     -cpu gen16b,ctop=on \
     -smp cpus=5,sockets=8,cores=4,maxcpus=32 \
     -device host-s390x-cpu,core-id=14 \
@@ -227,7 +229,7 @@ with vertical high entitlement.
 
 .. code-block:: bash
 
-  $ qemu-system-s390x -m 2G \
+  $ qemu-system-s390x -accel kvm -m 2G \
     -cpu gen16b,ctop=on \
     -smp cpus=1,sockets=8,cores=4,maxcpus=32 \
     \
-- 
2.26.2

Re: [PATCH] docs/s390: clarify even more that cpu-topology is KVM-only

[Nina Schoetterl-Glausch]

On Thu, 2024-03-14 at 18:22 +0100, Claudio Fontana wrote:
> At least for now cpu-topology is implemented only for KVM.
> 
> We already say this, but this tries to be more explicit,
> and also show it in the examples.
> 
> This adds a new reference in the introduction that we can point to,
> whenever we need to reference accelerators and how to select them.
> 
> Signed-off-by: Claudio Fontana <cfontana@suse.de>

Reviewed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Tested-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
(meaning I ran make html)

> ---
>  docs/system/introduction.rst       |  2 ++
>  docs/system/s390x/cpu-topology.rst | 14 ++++++++------
>  2 files changed, 10 insertions(+), 6 deletions(-)
> 
> diff --git a/docs/system/introduction.rst b/docs/system/introduction.rst
> index 51ac132d6c..746707eb00 100644
> --- a/docs/system/introduction.rst
> +++ b/docs/system/introduction.rst
> @@ -1,6 +1,8 @@
>  Introduction
>  ============
>  
> +.. _Accelerators:
> +
>  Virtualisation Accelerators
>  ---------------------------
>  
> diff --git a/docs/system/s390x/cpu-topology.rst b/docs/system/s390x/cpu-topology.rst
> index 5133fdc362..ca344e273c 100644
> --- a/docs/system/s390x/cpu-topology.rst
> +++ b/docs/system/s390x/cpu-topology.rst
> @@ -25,17 +25,19 @@ monitor polarization changes, see ``docs/devel/s390-cpu-topology.rst``.
>  Prerequisites
>  -------------
>  
> -To use the CPU topology, you need to run with KVM on a s390x host that
> -uses the Linux kernel v6.0 or newer (which provide the so-called
> +To use the CPU topology, you currently need to choose the KVM accelerator.
> +See :ref:`Accelerators` for more details about accelerators and how to select them.
> +
> +The s390x host needs to use a Linux kernel v6.0 or newer (which provides the so-called
>  ``KVM_CAP_S390_CPU_TOPOLOGY`` capability that allows QEMU to signal the
>  CPU topology facility via the so-called STFLE bit 11 to the VM).
>  
>  Enabling CPU topology
>  ---------------------
>  
> -Currently, CPU topology is only enabled in the host model by default.
> +Currently, CPU topology is enabled by default only in the "host" cpu model.
>  
> -Enabling CPU topology in a CPU model is done by setting the CPU flag
> +Enabling CPU topology in another CPU model is done by setting the CPU flag
>  ``ctop`` to ``on`` as in:
>  
>  .. code-block:: bash
> @@ -132,7 +134,7 @@ In the following machine we define 8 sockets with 4 cores each.
>  
>  .. code-block:: bash
>  
> -  $ qemu-system-s390x -m 2G \
> +  $ qemu-system-s390x -accel kvm -m 2G \
>      -cpu gen16b,ctop=on \
>      -smp cpus=5,sockets=8,cores=4,maxcpus=32 \
>      -device host-s390x-cpu,core-id=14 \
> @@ -227,7 +229,7 @@ with vertical high entitlement.
>  
>  .. code-block:: bash
>  
> -  $ qemu-system-s390x -m 2G \
> +  $ qemu-system-s390x -accel kvm -m 2G \
>      -cpu gen16b,ctop=on \
>      -smp cpus=1,sockets=8,cores=4,maxcpus=32 \
>      \

Re: [PATCH] docs/s390: clarify even more that cpu-topology is KVM-only

[Philippe Mathieu-Daudé]

On 14/3/24 18:22, Claudio Fontana wrote:
> At least for now cpu-topology is implemented only for KVM.
> 
> We already say this, but this tries to be more explicit,
> and also show it in the examples.
> 
> This adds a new reference in the introduction that we can point to,
> whenever we need to reference accelerators and how to select them.
> 
> Signed-off-by: Claudio Fontana <cfontana@suse.de>
> ---
>   docs/system/introduction.rst       |  2 ++
>   docs/system/s390x/cpu-topology.rst | 14 ++++++++------
>   2 files changed, 10 insertions(+), 6 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

Re: [PATCH] docs/s390: clarify even more that cpu-topology is KVM-only

[Thomas Huth]

On 14/03/2024 18.22, Claudio Fontana wrote:
> At least for now cpu-topology is implemented only for KVM.
> 
> We already say this, but this tries to be more explicit,
> and also show it in the examples.
> 
> This adds a new reference in the introduction that we can point to,
> whenever we need to reference accelerators and how to select them.
> 
> Signed-off-by: Claudio Fontana <cfontana@suse.de>
> ---
>   docs/system/introduction.rst       |  2 ++
>   docs/system/s390x/cpu-topology.rst | 14 ++++++++------
>   2 files changed, 10 insertions(+), 6 deletions(-)
> 
> diff --git a/docs/system/introduction.rst b/docs/system/introduction.rst
> index 51ac132d6c..746707eb00 100644
> --- a/docs/system/introduction.rst
> +++ b/docs/system/introduction.rst
> @@ -1,6 +1,8 @@
>   Introduction
>   ============
>   
> +.. _Accelerators:
> +
>   Virtualisation Accelerators
>   ---------------------------
>   
> diff --git a/docs/system/s390x/cpu-topology.rst b/docs/system/s390x/cpu-topology.rst
> index 5133fdc362..ca344e273c 100644
> --- a/docs/system/s390x/cpu-topology.rst
> +++ b/docs/system/s390x/cpu-topology.rst
> @@ -25,17 +25,19 @@ monitor polarization changes, see ``docs/devel/s390-cpu-topology.rst``.
>   Prerequisites
>   -------------
>   
> -To use the CPU topology, you need to run with KVM on a s390x host that
> -uses the Linux kernel v6.0 or newer (which provide the so-called
> +To use the CPU topology, you currently need to choose the KVM accelerator.
> +See :ref:`Accelerators` for more details about accelerators and how to select them.
> +
> +The s390x host needs to use a Linux kernel v6.0 or newer (which provides the so-called
>   ``KVM_CAP_S390_CPU_TOPOLOGY`` capability that allows QEMU to signal the
>   CPU topology facility via the so-called STFLE bit 11 to the VM).
>   
>   Enabling CPU topology
>   ---------------------
>   
> -Currently, CPU topology is only enabled in the host model by default.
> +Currently, CPU topology is enabled by default only in the "host" cpu model.

Thanks for your patch! I'd maybe write "cpu" with capital letters here like 
it is done in the other spots in this file. I can change that while picking 
up the patch.

  Thomas