diff options
Diffstat (limited to '')
| -rw-r--r-- | doc/user/task.t | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/doc/user/task.t b/doc/user/task.t index 40759fcaf6..a172a0c67b 100644 --- a/doc/user/task.t +++ b/doc/user/task.t @@ -1,5 +1,5 @@ @c -@c COPYRIGHT (c) 1988-2008. +@c COPYRIGHT (c) 1988-2014. @c On-Line Applications Research Corporation (OAR). @c All rights reserved. @@ -340,6 +340,13 @@ containing the task's private "global" data. A critical point with per-task variables is that each task must separately request that the same global variable is per-task private. +@b{WARNING}: Per-Task variables are inherently broken on SMP systems. They +only work correctly when there is one task executing in the system and +that task is the logical owner of the value in the per-task variable's +location. There is no way for a single memory image to contain the +correct value for each task executing on each core. Consequently, +per-task variables are disabled in SMP configurations of RTEMS. + @subsection Building a Task Attribute Set @cindex task attributes, building @@ -1779,6 +1786,9 @@ is to have a single task variable that is a pointer to a dynamically allocated structure containing the task's private `global' data. In this case the destructor function could be `free'. +Per-task variables are disabled in SMP configurations and this service +is not available. + @page @subsection TASK_VARIABLE_GET - Obtain value of a per task variable @@ -1832,6 +1842,9 @@ will optimize it correctly. In this case both the pointer @code{task_variable_value} and data referenced by @code{task_variable_value} should be considered volatile. +Per-task variables are disabled in SMP configurations and this service +is not available. + @page @subsection TASK_VARIABLE_DELETE - Remove per task variable @@ -1874,4 +1887,6 @@ This directive removes the given location from a task's context. @subheading NOTES: -NONE +Per-task variables are disabled in SMP configurations and this service +is not available. + |