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docs: Update domain's region permissions and requirements

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Updated the various permissions bits available for domains
defined in DT node and restrictions on them.

Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Tested-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Himanshu Chauhan
2023-01-09 05:20:43 +00:00
committed by Anup Patel
parent 59a08cd7d6
commit 001106d19b
1 changed files with 10 additions and 2 deletions
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12
docs/domain_support.md
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@@ -160,8 +160,16 @@ The DT properties of a domain instance DT node are as follows:
* **regions** (Optional) - The list of domain memory region DT node phandle
and access permissions for the domain instance. Each list entry is a pair
of DT node phandle and access permissions. The access permissions are
represented as a 32bit bitmask having bits: **readable** (BIT[0]),
**writeable** (BIT[1]), **executable** (BIT[2]), and **M-mode** (BIT[3]).
represented as a 32bit bitmask having bits: **M readable** (BIT[0]),
**M writeable** (BIT[1]), **M executable** (BIT[2]), **SU readable**
(BIT[3]), **SU writable** (BIT[4]), and **SU executable** (BIT[5]).
The enforce permission bit (BIT[6]), if set, will lock the permissions
in the PMP. This will enforce the permissions on M-mode as well which
otherwise will have unrestricted access. This bit must be used with
caution because no changes can be made to a PMP entry once its locked
until the hart is reset.
Any region of a domain defined in DT node cannot have only M-bits set
in access permissions i.e. it cannot be an m-mode only accessible region.
* **boot-hart** (Optional) - The DT node phandle of the HART booting the
domain instance. If coldboot HART is assigned to the domain instance then
this DT property is ignored and the coldboot HART is assumed to be the