On 10/6/25 2:29 PM, Shameer Kolothum wrote:
The virt machine now supports creating multiple SMMUv3 instances, each
associated with a separate PCIe root complex.
Update the documentation with an example.
Signed-off-by: Shameer Kolothum <[email protected]>
---
docs/system/arm/virt.rst | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/docs/system/arm/virt.rst b/docs/system/arm/virt.rst
index 10cbffc8a7..2e0e8196be 100644
--- a/docs/system/arm/virt.rst
+++ b/docs/system/arm/virt.rst
@@ -37,7 +37,19 @@ The virt board supports:
- An RTC
- The fw_cfg device that allows a guest to obtain data from QEMU
- A PL061 GPIO controller
-- An optional SMMUv3 IOMMU
+- An optional machine-wide SMMUv3 IOMMU
I suggest a '(see example below)' at the end of the above line.
+- User-creatable SMMUv3 devices
+
+ Allows instantiating multiple SMMUv3 devices, each associated with
+ a separate PCIe root complex. This is only allowed if the machine-wide
+ SMMUv3(``iommu=smmuv3``) is not used.
+
+ Example::
+
+ -device arm-smmuv3,primary-bus=pcie.0,id=smmuv3.0
+ ...
+ -device pxb-pcie,id=pcie.1
+ -device arm-smmuv3,primary-bus=pcie.1,id=smmuv3.1
I like the detail; and wish it was done for many more of the -<option> above it,
e.g., PCIe, MSI, etc.
- hotpluggable DIMMs
- hotpluggable NVDIMMs
- An MSI controller (GICv2M or ITS). GICv2M is selected by default along
@@ -176,7 +188,8 @@ iommu
``none``
Don't create an IOMMU (the default)
``smmuv3``
- Create an SMMUv3
+ Create a machine-wide SMMUv3. Alternatively, SMMUv3 devices can be
s/Alternatively, SMMUv3/Alternatively, non-machine-wide SMMUv3/
Add:
'Note: user-creatable SMMUv3 devices cannot be instantiated if a machine-wide
SMMUv3 is instantiated.'
Or should this section be moved up and after the updated 'optional machine-wide
SMMUv3 IOMMU' above?
So all-things SMMUv3 are in the same doc area, and not split up as they are
now, and not worsen over time as
more things (accelerated SMMUv3 documentation) is added
+ instantiated directly using the ``-device`` option (see example above).
default-bus-bypass-iommu
Set ``on``/``off`` to enable/disable `bypass_iommu
Thanks for the added documentation; more is better!
- Don
