linux_dsm_epyc7002/arch/nds32
Vincent Chen 44e92e0364 nds32: support denormalized result through FP emulator
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>
2018-11-22 18:13:27 +08:00
..
boot nds32: Perf porting 2018-11-06 18:01:40 +08:00
configs nds32: defconfig 2018-02-22 10:44:35 +08:00
include nds32: support denormalized result through FP emulator 2018-11-22 18:13:27 +08:00
kernel nds32: support denormalized result through FP emulator 2018-11-22 18:13:27 +08:00
lib nds32: Fix the symbols undefined issue by exporting them. 2018-05-23 13:26:20 +08:00
math-emu nds32: support denormalized result through FP emulator 2018-11-22 18:13:27 +08:00
mm nds32: Perf porting 2018-11-06 18:01:40 +08:00
Kconfig nds32: nds32 FPU port 2018-11-22 18:13:13 +08:00
Kconfig.cpu nds32: support denormalized result through FP emulator 2018-11-22 18:13:27 +08:00
Kconfig.debug Kconfig: consolidate the "Kernel hacking" menu 2018-08-02 08:06:48 +09:00
Makefile nds32: Support FP emulation 2018-11-22 18:13:21 +08:00