Assigning Physical Resources to Domains

The Logical Domains Manager automatically selects the physical resources to be assigned to a domain. The Oracle VM Server for SPARC 3.0 software also enables expert administrators to explicitly choose the physical resources to assign to or remove from a domain.

Resources that you explicitly assign are called named resources. Resources that are automatically assigned are called anonymous resources.

Caution - Do not assign named resources unless you are an expert administrator.

You can explicitly assign physical resources to the control domain and to guest domains. Because the control domain remains active, the control domain might optionally be in a delayed reconfiguration before you make physical resource assignments. Or, a delayed reconfiguration is automatically triggered when you make physical assignments. See Managing Physical Resources on the Control Domain. For information about physical resource restrictions, see Restrictions for Managing Physical Resources on Domains.

You can explicitly assign the following physical resources to the control domain and to guest domains:

Physical CPUs. Assign the physical core IDs to the domain by setting the cid property.

The cid property should only be used by an administrator who is knowledgeable about the topology of the system to be configured. This advanced configuration feature enforces specific allocation rules and might affect the overall performance of the system.

You can set this property by running any of the following commands:
```
# ldm add-core cid=core-ID[,core-ID[,...]] ldom
# ldm set-core cid=core-ID[,core-ID[,...]] ldom
# ldm rm-core [-f] cid=core-ID[,core-ID[,...]] ldom
```
If you specify a core ID as the value of the cid property, core-ID is explicitly assigned to or removed from the domain.
Physical memory. Assign a set of contiguous physical memory regions to a domain by setting the mblock property. Each physical memory region is specified as a physical memory start address and a size.

The mblock property should only be used by an administrator who is knowledgeable about the topology of the system to be configured. This advanced configuration feature enforces specific allocation rules and might affect the overall performance of the system.

You can set this property by running any of the following commands:
```
# ldm add-mem mblock=PA-start:size[,PA-start:size[,...]] ldom
# ldm set-mem mblock=PA-start:size[,PA-start:size[,...]] ldom
# ldm rm-mem mblock=PA-start:size[,PA-start:size[,...]] ldom
```
To assign a memory block to or remove it from a domain, set the mblock property. A valid value includes a physical memory starting address (PA-start) and a memory block size (size), separated by a colon (:).

Note - You cannot use dynamic reconfiguration (DR) to move memory or core resources between running domains when you set the mblock or cid property. To move resources between domains, ensure that the domains are in a bound or inactive state. For information about managing physical resources on the control domain, see Managing Physical Resources on the Control Domain.

You can use the ldm list-constraints command to view the resource constraints for domains. The physical-bindings constraint specifies which resource types have been physically assigned to a domain. When a domain is created, the physical-bindings constraint is unset until a physical resource is assigned to that domain. By setting the mblock property, the physical-bindings constraint is set to memory. Likewise, by setting the cid property, the physical-bindings constraint is set to core. If both the cid and mblock properties are set, the physical-bindings constraint is set to core,memory.

How to Remove the `physical-bindings` Constraint

To remove the physical-bindings constraint for a guest domain, you must first remove all physically bound resources.

Unbind the domain.
```
# ldm unbind domain
```

Remove the named resources.

Named cores.
```
# ldm set-core cid=core-ID domain
```

Named memory.

# ldm set-mem mblock=PA-start:size domain

Add CPU or memory resources.

CPU resource.
```
# ldm add-vcpu number domain
```
Memory resource.
```
# ldm add-mem size[unit] domain
```

Rebind the domain.
```
# ldm bind domain
```

How to Remove All Non-Physically Bound Resources

To constrain guest domains that do not have the physical-bindings constraint, you must first remove all non-physically bound resources.

Unbind the domain.
```
# ldm unbind domain
```
Set the number of resources to 0.
- CPU resource.
```
# ldm set-core 0 domain
```
- Memory resource.
```
# ldm set-mem 0 domain
```

Add CPU or memory that is physically bound.

CPU resource.
```
# ldm add-core cid=core-ID domain
```

Memory resource.

# ldm add-mem mblock=PA-start:size domain

Rebind the domain.
```
# ldm bind domain
```

Managing Physical Resources on the Control Domain

To constrain or remove the physical-bindings constraint from the control domain, follow the appropriate steps in the previous section. However, instead of unbinding the domain, place the control domain in a delayed reconfiguration.

A change of constraint between anonymous resources and physically bound named resources auto-triggers a delayed reconfiguration. You can still explicitly enter a delayed reconfiguration by using the ldm start-reconf primary command.

As with any delayed reconfiguration change, you must perform a reboot of the domain, in this case the control domain, to complete the process.

Note - When the control domain is in delayed reconfiguration mode, you can perform unlimited memory assignments by using the ldm add-mem and ldm rm-mem commands on the control domain. However, you can perform only one core assignment to the control domain by using the ldm set-core command.

Restrictions for Managing Physical Resources on Domains

The following restrictions apply to the assignment of physical resources:

You cannot make physical and non-physical memory bindings, or physical and non-physical core bindings, in the same domain.
You can have non-physical memory and physical core bindings, or non-physical core and physical memory bindings, in the same domain.
When you add a physical resource to a domain, the corresponding resource type becomes constrained as a physical binding.
Attempts to add anonymous CPUs to or remove them from a domain where physical-bindings=core will fail.
For unbound resources, the allocation and checking of the resources can only occur when you run the ldm bind command.
When removing physical memory from a domain, you must remove the exact physical memory block that was previously added.
Physical memory ranges must not overlap.
You can only use the ldm add-core cid= or ldm set-core cid= command to assign a physical resource to a domain.
If you use the ldm add-mem mblock= or ldm set-mem mblock= command to assign multiple physical memory blocks, the addresses and sizes are checked immediately for collisions with other bindings.
A domain that has partial cores assigned to it can use the whole-core semantics if the remaining CPUs of those cores are free and available.

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