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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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44e92e0364
Currently, the nds32 FPU dose not support the arithmetic of denormalized
number. When the nds32 FPU finds the result of the instruction is a
denormlized number, the nds32 FPU considers it to be an underflow condition
and rounds the result to an appropriate number. It may causes some loss
of precision. This commit proposes a solution to re-execute the
instruction by the FPU emulator to enhance the precision. To transfer
calculations from user space to kernel space, this feature will enable
the underflow exception trap by default. Enabling this feature may cause
some side effects:
1. Performance loss due to extra FPU exception
2. Need another scheme to control real underflow trap
A new parameter, UDF_trap, which is belong to FPU context is used
to control underflow trap.
User can configure this feature via CONFIG_SUPPORT_DENORMAL_ARITHMETIC
Signed-off-by: Vincent Chen <vincentc@andestech.com>
Acked-by: Greentime Hu <greentime@andestech.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>
14 lines
415 B
C
14 lines
415 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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/* Copyright (C) 2005-2018 Andes Technology Corporation */
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#ifndef _ASM_SETFPUTRAP
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#define _ASM_SETFPUTRAP
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/*
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* Options for setfputrap system call
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*/
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#define DISABLE_UDFTRAP 0 /* disable underflow exception trap */
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#define ENABLE_UDFTRAP 1 /* enable undeflos exception trap */
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#define GET_UDFTRAP 2 /* only get undeflos exception trap status */
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#endif /* _ASM_CACHECTL */
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