4bf2a5b045
CpuPause() might allow the CPU to go into a lower power state state while we spin. On X86, CpuPause() executes a PAUSE instruction which the Intel and AMD specs describe as follows: Intel: "PAUSE: An additional function of the PAUSE instruction is to reduce the power consumed by a processor while executing a spin loop. A processor can execute a spin-wait loop extremely quickly, causing the processor to consume a lot of power while it waits for the resource it is spinning on to become available. Inserting a pause instruction in a spin-wait loop greatly reduces the processor?s power consumption." AMD: "PAUSE: Improves the performance of spin loops, by providing a hint to the processor that the current code is in a spin loop. The processor may use this to optimize power consumption while in the spin loop. Architecturally, this instruction behaves like a NOP instruction." On RISC-V and ARM64, CpuPause() executes a NOP, which is no worse than the tight loop we have. Cc: Liming Gao <gaoliming@byosoft.com.cn> Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com> Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com> Reviewed-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>
35 lines
684 B
C
35 lines
684 B
C
/** @file
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Base Library CPU Functions for all architectures.
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Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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**/
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#include <Base.h>
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#include <Library/BaseLib.h>
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/**
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Executes an infinite loop.
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Forces the CPU to execute an infinite loop. A debugger may be used to skip
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past the loop and the code that follows the loop must execute properly. This
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implies that the infinite loop must not cause the code that follow it to be
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optimized away.
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**/
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VOID
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EFIAPI
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CpuDeadLoop (
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VOID
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)
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{
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volatile UINTN Index;
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for (Index = 0; Index == 0;) {
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CpuPause();
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}
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}
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