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cl_khr_external_semaphore: Clarify language #938

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Jul 9, 2024
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cl_khr_external_semaphore: Clarify language #938

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cl_khr_external_semaphore: Clarify language
lakshmih Apr 1, 2024
cb683e7
Fix table format
lakshmih Jun 18, 2024
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80 changes: 23 additions & 57 deletions api/opencl_runtime_layer.asciidoc
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Original file line number Diff line number Diff line change
Expand Up @@ -12866,6 +12866,10 @@ ifdef::cl_khr_external_semaphore[]

[open,refpage='clGetSemaphoreHandleForTypeKHR',desc='Export external handle from a semaphore',type='protos']
--

Export operations have the same transference as the specified handle type's import operations. Additionally, exporting a semaphore payload to a handle with copy transference has the same side effects on the source semaphore's payload as executing a semaphore wait operation.

Please refer to handle specific documentation for more details on transference requirements per handle type.
To export an external handle from a semaphore, call the function

include::{generated}/api/protos/clGetSemaphoreHandleForTypeKHR.txt[]
Expand Down Expand Up @@ -12919,53 +12923,19 @@ Otherwise, it returns one of the following errors:

=== Importing Semaphore External Handles

Applications can import a semaphore payload into an existing semaphore using
an external semaphore handle.
The effects of the import operation will be either temporary or permanent,
as specified by the application.
If the import is temporary, the implementation must restore the semaphore to
its prior permanent state after submitting the next semaphore wait
operation.
Performing a subsequent temporary import on a semaphore before performing a
semaphore wait has no effect on this requirement; the next wait submitted on
the semaphore must still restore its last permanent state.
A permanent payload import behaves as if the target semaphore was destroyed,
and a new semaphore was created with the same handle but the imported
payload.
Because importing a semaphore payload temporarily or permanently detaches
the existing payload from a semaphore, similar usage restrictions to those
applied to {clReleaseSemaphoreKHR} are applied to any command that imports a
semaphore payload.
Which of these import types is used is referred to as the import operation's
permanence.
Each handle type supports either one or both types of permanence.

The implementation must perform the import operation by either referencing
or copying the payload referred to by the specified external semaphore
handle, depending on the handle's type.
The import method used is referred to as the handle type's transference.
When using handle types with reference transference, importing a payload to
a semaphore adds the semaphore to the set of all semaphores sharing that
payload.
This set includes the semaphore from which the payload was exported.
Semaphore signaling and waiting operations performed on any semaphore in the
set must behave as if the set were a single semaphore.
Importing a payload using handle types with copy transference creates a
duplicate copy of the payload at the time of import, but makes no further
reference to it.
Semaphore signaling and waiting operations performed on the target of copy
imports must not affect any other semaphore or payload.

Export operations have the same transference as the specified handle type's
import operations.
Additionally, exporting a semaphore payload to a handle with copy
transference has the same side effects on the source semaphore's payload as
executing a semaphore wait operation.
If the semaphore was using a temporarily imported payload, the semaphore's
prior permanent payload will be restored.

Please refer to handle specific specifications for more details on
transference and permanence requirements specific to handle type.
Applications can import a semaphore payload by creating a semaphore from an external handle. The
implementation must perform the import operation by either referencing or copying the payload
referred to by the specified external semaphore handle, depending on the handle's type. When using
handle types with reference transference, importing a payload to a semaphore adds the semaphore to
the set of all semaphores sharing that payload. This set includes the semaphore from which the payload
was exported. Semaphore signaling and waiting operations performed on any semaphore in the set must
behave as if the set were a single semaphore. Importing a payload using handle types with copy
transference creates a duplicate copy of the payload at the time of import, but makes no further
reference to it. Semaphore signaling and waiting operations performed on the target of copy imports
must not affect any other semaphore or payload.

Please refer to handle specific documentation for more details on transference requirements per
handle type.
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This feels like a good step forward. I'm wondering whether we should mention re-import commands in this paragraph. In the end the command was made specific to sync_fd while this paragraph is documents generic bits of behaviour.



=== Descriptions of External Semaphore Handle Types
Expand Down Expand Up @@ -13034,17 +13004,16 @@ descriptor when exporting a {CL_SEMAPHORE_HANDLE_SYNC_FD_KHR} from a

endif::cl_khr_external_semaphore_sync_fd[]

.Transference and Permanence Properties for File Descriptor Handles
[width="100%",cols="60%,<20%,<20%",options="header"]
.Transference Properties for File Descriptor Handles
[width="100%",cols="60%,<40%",options="header"]
|====
| Handle Type | Transference | Permanence
| Handle Type | Transference
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Since we're modifying the number of table columns I think we also need to update the table contents for CL_SEMAPHORE_HANDLE_SYNC_FD_KHR below.


ifdef::cl_khr_external_semaphore_opaque_fd[]
| {CL_SEMAPHORE_HANDLE_OPAQUE_FD_KHR_anchor}

include::{generated}/api/version-notes/CL_SEMAPHORE_HANDLE_OPAQUE_FD_KHR.asciidoc[]
| Reference
| Temporary, Permanent
endif::cl_khr_external_semaphore_opaque_fd[]

ifdef::cl_khr_external_semaphore_sync_fd[]
Expand Down Expand Up @@ -13130,24 +13099,21 @@ a semaphore from an external handle:

endif::cl_khr_external_semaphore_win32[]

.Transference and Permanence Properties for NT Handle Types
[width="100%",cols="60%,<20%,<20%",options="header"]
.Transference Properties for NT Handle Types
[width="100%",cols="60%,<40%",options="header"]
|====
| Handle Type | Transference | Permanence
| Handle Type | Transference

ifdef::cl_khr_external_semaphore_win32[]
| {CL_SEMAPHORE_HANDLE_OPAQUE_WIN32_KHR_anchor}

include::{generated}/api/version-notes/CL_SEMAPHORE_HANDLE_OPAQUE_WIN32_KHR.asciidoc[]
| Reference
| Temporary, Permanent
| {CL_SEMAPHORE_HANDLE_OPAQUE_WIN32_KMT_KHR_anchor}

include::{generated}/api/version-notes/CL_SEMAPHORE_HANDLE_OPAQUE_WIN32_KMT_KHR.asciidoc[]
| Reference
| Temporary, Permanent
endif::cl_khr_external_semaphore_win32[]
|====

// TODO Why "Windows handles" here but "NT handles" elsewhere?

Expand Down