[PATCH v3 9/9] docs: document WID DT properties

[Anup Patel]

On Tue, Oct 27, 2026 at 2:06 PM Yu-Chien Peter Lin <peter.lin at sifive.com> wrote:
>
> Add "wid" and "widdeleg" properties to domain instance node
> documentation and example DT. Add a "Root Domain Node" section
> describing the "root" subnode under the domain configuration
> node for root domain WID configuration
>
> Signed-off-by: Yu-Chien Peter Lin <peter.lin at sifive.com>
> ---
> Change v2->v3:
> - Mark 'wid' property as mandatory when Smlwid is present for both root
>   and domain instance nodes.
> - Remove mention of M-mode WID fallback when 'wid' is absent.
> ---
>  docs/domain_support.md | 36 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 36 insertions(+)
>
> diff --git a/docs/domain_support.md b/docs/domain_support.md
> index 51737218..54327e8d 100644
> --- a/docs/domain_support.md
> +++ b/docs/domain_support.md
> @@ -56,6 +56,8 @@ has following details:
>    domain. This can be either S-mode or U-mode.
>  * **system_reset_allowed** - Is domain allowed to reset the system?
>  * **system_suspend_allowed** - Is domain allowed to suspend the system?
> +* **wid** - World ID for the domain
> +* **widdeleg** - World ID delegation bitmask for the domain
>
>  The memory regions represented by **regions** in **struct sbi_domain** have
>  following additional constraints to align with RISC-V PMP requirements:
> @@ -98,6 +100,8 @@ following manner:
>    is the next mode for the ROOT domain
>  * **system_reset_allowed** - The ROOT domain is allowed to reset the system
>  * **system_suspend_allowed** - The ROOT domain is allowed to suspend the system
> +* **wid** - Configurable World ID for the ROOT domain
> +* **widdeleg** - Configurable World ID delegation bitmask for the ROOT domain
>
>  Domain Effects
>  --------------
> @@ -131,6 +135,22 @@ The DT properties of a domain configuration DT node are as follows:
>  * **compatible** (Mandatory) - The compatible string of the domain
>    configuration. This DT property should have value *"opensbi,domain,config"*
>
> +### Root Domain Node
> +
> +The root domain WID configuration is described in a **root** subnode under
> +the domain configuration DT node. This subnode does not have a compatible
> +string.
> +
> +The DT properties of the root domain node are as follows:
> +
> +* **wid** (Mandatory if Smlwid is present) - The 32-bit World ID for
> +  lower-privilege modes (S/U-mode) for the ROOT domain. If the hart
> +  supports the Smlwid extension, this property must be provided.
> +* **widdeleg** (Optional) - The 64 bit World ID delegation bitmask for
> +  the ROOT domain. If present, OpenSBI writes this value to **mwiddeleg**
> +  when entering the ROOT domain (requires Smwiddeleg extension). If absent,
> +  clears **mwiddeleg** to disable S-mode WID delegation.
> +

Let's define mandatory compatible DT property for root domain DT node
as well. The suggestion in PATCH3 will allow you to do that.

>  ### Domain Memory Region Node
>
>  The domain memory region DT node describes details of a memory region and
> @@ -205,6 +225,13 @@ The DT properties of a domain instance DT node are as follows:
>    whether the domain instance is allowed to do system reset.
>  * **system-suspend-allowed** (Optional) - A boolean flag representing
>    whether the domain instance is allowed to do system suspend.
> +* **wid** (Mandatory if Smlwid is present) - The 32-bit World ID for
> +  lower-privilege modes (S/U-mode) for the domain instance. If the hart
> +  supports the Smlwid extension, this property must be provided.
> +* **widdeleg** (Optional) - The 64 bit World ID delegation bitmask for
> +  the domain instance. If present, OpenSBI writes this value to **mwiddeleg**
> +  on context switch into this domain (requires Smwiddeleg extension). If absent,
> +  clears **mwiddeleg** to disable S-mode WID delegation.
>
>  ### Assigning HART To Domain Instance
>
> @@ -260,6 +287,11 @@ be done:
>                  order = <64>;
>              };
>
> +            root {
> +                wid = <3>;
> +                widdeleg = <0x0 0x0>;
> +            };
> +
>              tdomain: trusted-domain {
>                  compatible = "opensbi,domain,instance";
>                  possible-harts = <&cpu0>;
> @@ -268,6 +300,8 @@ be done:
>                  next-arg1 = <0x0 0x0>;
>                  next-addr = <0x0 0x80100000>;
>                  next-mode = <0x0>;
> +                wid = <1>;
> +                widdeleg = <0x0 0x6>;
>                  system-reset-allowed;
>                  system-suspend-allowed;
>              };
> @@ -276,6 +310,8 @@ be done:
>                  compatible = "opensbi,domain,instance";
>                  possible-harts = <&cpu1 &cpu2 &cpu3 &cpu4>;
>                  regions = <&tmem 0x0>, <&tuart 0x0>, <&allmem 0x3f>;
> +                wid = <0>;
> +                widdeleg = <0x0 0x1>;
>              };
>          };
>      };
> --
> 2.43.7
>

Regards,
Anup