kconfig: Improve architecture floating point symbol descriptions

This commit reworks the symbol descriptions for `CONFIG_FPU` and
`CONFIG_FP_SHARING`, in order to provide more details and clarify any
ambiguity between the two symbols.

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>
This commit is contained in:
Stephanos Ioannidis 2020-04-24 14:06:37 +09:00 committed by Carles Cufí
commit 4f4e85c035

View file

@ -520,23 +520,38 @@ config MPU_GAP_FILLING
documentation for more information on how this option is
used.
menuconfig FPU
bool "Floating point"
menu "Floating Point Options"
config FPU
bool "Enable floating point unit (FPU)"
depends on CPU_HAS_FPU
depends on ARC || ARM || RISCV || X86
help
This option allows threads to use the floating point registers.
By default, only a single thread may use the registers.
This option enables the hardware Floating Point Unit (FPU), in order to
support using the floating point registers and instructions.
Disabling this option means that any thread that uses a
floating point register will get a fatal exception.
When this option is enabled, by default, threads may use the floating
point registers only in an exclusive manner, and this usually means that
only one thread may perform floating point operations.
If it is necessary for multiple threads to perform concurrent floating
point operations, the "FPU register sharing" option must be enabled to
preserve the floating point registers across context switches.
Note that this option cannot be selected for the platforms that do not
include a hardware floating point unit; the floating point support for
those platforms is dependent on the availability of the toolchain-
provided software floating point library.
config FP_SHARING
bool "Floating point register sharing"
bool "FPU register sharing"
depends on FPU
help
This option allows multiple threads to use the floating point
registers.
This option enables preservation of the hardware floating point registers
across context switches to allow multiple threads to perform concurrent
floating point operations.
endmenu
config ARCH
string