97 lines
3.8 KiB
C
97 lines
3.8 KiB
C
/* strtask.c - Intel nanokernel APIs to start a task */
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/*
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* Copyright (c) 2010-2014 Wind River Systems, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1) Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* 2) Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* 3) Neither the name of Wind River Systems nor the names of its contributors
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* may be used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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DESCRIPTION
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Intel-specific parts of start_task(). Only FP functionality currently.
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*/
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#ifdef CONFIG_MICROKERNEL
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#include <start_task_arch.h>
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/*
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* The following IA-32-specific task group is used for tasks that use SSE
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* instructions. It is *not* formally reserved by SysGen for this purpose.
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* See comments in nanocontext.c regarding the use of SSE_GROUP, and comments
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* in task.h regarding task groups reserved by SysGen.
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*
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* This identifier corresponds to the first user-defined task group.
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* It must be updated if any changes are made to the reserved groups.
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*/
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#define SSE_GROUP 0x10
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/*******************************************************************************
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*
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* _StartTaskArch - Intel-specifc parts of task initialization
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*
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* RETURNS: N/A
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*/
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void _StartTaskArch(
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struct k_proc *X, /* ptr to task control block */
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unsigned int *pOpt /* context options container */
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)
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{
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/*
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* The IA-32 nanokernel implementation uses the USE_FP bit in the
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* tCCS->flags structure as a "dirty bit". The USE_FP flag bit will be
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* set whenever a context uses any non-integer capability, whether it's
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* just the x87 FPU capability, SSE instructions, or a combination of
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* both. The USE_SSE flag bit will only be set if a context uses SSE
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* instructions.
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*
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* However, callers of nanoFiberStart(), task_fiber_start(), or even
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* _NewContext() don't need to follow the protocol used by the IA-32
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* nanokernel w.r.t. managing the tCCS->flags field. If a context
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* will be utilizing just the x87 FPU capability, then the USE_FP
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* option bit is specified. If a context will be utilizing SSE
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* instructions (and possibly x87 FPU capability), then only the
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* USE_SSE option bit needs to be specified.
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*
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* Likewise, the placement of tasks into "groups" doesn't need to follow
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* the protocol used by the IA-32 nanokernel w.r.t. managing the
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* tCCS->flags field. If a task will utilize just the x87 FPU
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*capability,
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* then the task only needs to be placed in the FPU_GROUP group.
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* If a task utilizes SSE instructions (and possibly x87 FPU
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*capability),
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* then the task only needs to be placed in the SSE_GROUP group.
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*/
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*pOpt |= (X->Group & SSE_GROUP) ? USE_SSE
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: (X->Group & FPU_GROUP) ? USE_FP : 0;
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}
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#endif /* CONFIG_MICROKERNEL */
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