diff options
Diffstat (limited to 'docs/specs')
| -rw-r--r-- | docs/specs/riscv-iommu.rst | 30 |
1 files changed, 27 insertions, 3 deletions
diff --git a/docs/specs/riscv-iommu.rst b/docs/specs/riscv-iommu.rst index 463f4cffb6..b1538c9ead 100644 --- a/docs/specs/riscv-iommu.rst +++ b/docs/specs/riscv-iommu.rst @@ -6,9 +6,9 @@ RISC-V IOMMU support for RISC-V machines QEMU implements a RISC-V IOMMU emulation based on the RISC-V IOMMU spec version 1.0 `iommu1.0`_. -The emulation includes a PCI reference device, riscv-iommu-pci, that QEMU -RISC-V boards can use. The 'virt' RISC-V machine is compatible with this -device. +The emulation includes a PCI reference device (riscv-iommu-pci) and a platform +bus device (riscv-iommu-sys) that QEMU RISC-V boards can use. The 'virt' +RISC-V machine is compatible with both devices. riscv-iommu-pci reference device -------------------------------- @@ -83,6 +83,30 @@ Several options are available to control the capabilities of the device, namely: - "s-stage": enable s-stage support - "g-stage": enable g-stage support +riscv-iommu-sys device +---------------------- + +This device implements the RISC-V IOMMU emulation as a platform bus device that +RISC-V boards can use. + +For the 'virt' board the device is disabled by default. To enable it use the +'iommu-sys' machine option: + +.. code-block:: bash + + $ qemu-system-riscv64 -M virt,iommu-sys=on (...) + +There is no options to configure the capabilities of this device in the 'virt' +board using the QEMU command line. The device is configured with the following +riscv-iommu options: + +- "ioatc-limit": default value (2Mb) +- "intremap": enabled +- "ats": enabled +- "off": on (DMA disabled) +- "s-stage": enabled +- "g-stage": enabled + .. _iommu1.0: https://github.com/riscv-non-isa/riscv-iommu/releases/download/v1.0/riscv-iommu.pdf .. _linux-v8: https://lore.kernel.org/linux-riscv/cover.1718388908.git.tjeznach@rivosinc.com/ |