config BR2_ARM_CPU_MAYBE_HAS_NEON
bool
+# for some cores, VFPv2 is optional
+config BR2_ARM_CPU_MAYBE_HAS_VFPV2
+ bool
+
+config BR2_ARM_CPU_HAS_VFPV2
+ bool
+
+# for some cores, VFPv3 is optional
+config BR2_ARM_CPU_MAYBE_HAS_VFPV3
+ bool
+ select BR2_ARM_CPU_MAYBE_HAS_VFPV2
+
+config BR2_ARM_CPU_HAS_VFPV3
+ bool
+ select BR2_ARM_CPU_HAS_VFPV2
+
+# for some cores, VFPv4 is optional
+config BR2_ARM_CPU_MAYBE_HAS_VFPV4
+ bool
+ select BR2_ARM_CPU_MAYBE_HAS_VFPV3
+
+config BR2_ARM_CPU_HAS_VFPV4
+ bool
+ select BR2_ARM_CPU_HAS_VFPV3
+
choice
prompt "Target Architecture Variant"
depends on BR2_arm || BR2_armeb
bool "arm10t"
config BR2_arm1136jf_s_r0
bool "arm1136jf_s rev0"
+ select BR2_ARM_CPU_HAS_VFPV2
config BR2_arm1136jf_s_r1
bool "arm1136jf_s rev1"
+ select BR2_ARM_CPU_HAS_VFPV2
config BR2_arm1176jz_s
bool "arm1176jz-s"
config BR2_arm1176jzf_s
bool "arm1176jzf-s"
+ select BR2_ARM_CPU_HAS_VFPV2
config BR2_cortex_a5
bool "cortex-A5"
select BR2_ARM_CPU_MAYBE_HAS_NEON
+ select BR2_ARM_CPU_MAYBE_HAS_VFPV4
config BR2_cortex_a7
bool "cortex-A7"
select BR2_ARM_CPU_HAS_NEON
+ select BR2_ARM_CPU_HAS_VFPV4
config BR2_cortex_a8
bool "cortex-A8"
select BR2_ARM_CPU_HAS_NEON
+ select BR2_ARM_CPU_HAS_VFPV3
config BR2_cortex_a9
bool "cortex-A9"
select BR2_ARM_CPU_MAYBE_HAS_NEON
+ select BR2_ARM_CPU_MAYBE_HAS_VFPV3
config BR2_cortex_a15
bool "cortex-A15"
select BR2_ARM_CPU_HAS_NEON
+ select BR2_ARM_CPU_HAS_VFPV4
config BR2_fa526
bool "fa526/626"
config BR2_pj4
bool "pj4"
+ select BR2_ARM_CPU_HAS_VFPV3
config BR2_strongarm
bool "strongarm sa110/sa1100"
config BR2_xscale
choice
prompt "Target ABI"
depends on BR2_arm || BR2_armeb
- depends on BR2_DEPRECATED
default BR2_ARM_EABI
help
- Application Binary Interface to use
+ Application Binary Interface to use. The Application Binary
+ Interface describes the calling conventions (how arguments
+ are passed to functions, how the return value is passed, how
+ system calls are made, etc.).
-config BR2_ARM_EABI_CHOICE
+config BR2_ARM_EABI
bool "EABI"
-endchoice
+ help
+ The EABI is currently the standard ARM ABI, which is used in
+ most projects. It supports both the 'soft' floating point
+ model (in which floating point instructions are emulated in
+ software) and the 'softfp' floating point model (in which
+ floating point instructions are executed using an hardware
+ floating point unit, but floating point arguments to
+ functions are passed in integer registers).
-config BR2_ARM_EABI
- def_bool y
+ The 'softfp' floating point model is link-compatible with
+ the 'soft' floating point model, i.e you can link a library
+ built 'soft' with some other code built 'softfp'.
-config BR2_ARM_SOFT_FLOAT
- bool "Use soft-float"
- default y
- select BR2_SOFT_FLOAT
+ However, passing the floating point arguments in integer
+ registers is a bit inefficient, so if your ARM processor has
+ a floating point unit, and you don't have pre-compiled
+ 'soft' or 'softfp' code, using the EABIhf ABI will provide
+ better floating point performances.
+
+ If your processor does not have a floating point unit, then
+ you must use this ABI.
+
+config BR2_ARM_EABIHF
+ bool "EABIhf"
+ depends on BR2_ARM_CPU_MAYBE_HAS_VFPV2 || BR2_ARM_CPU_HAS_VFPV2
help
- If your target CPU does not have a Floating Point Unit (FPU)
- or a kernel FPU emulator, but you still wish to support
- floating point functions, then everything will need to be
- compiled with soft floating point support (-msoft-float).
+ The EABIhf is an extension of EABI which supports the 'hard'
+ floating point model. This model uses the floating point
+ unit to execute floating point instructions, and passes
+ floating point arguments in floating point registers.
+
+ It is more efficient than EABI for floating point related
+ workload. However, it does not allow to link against code
+ that has been pre-built for the 'soft' or 'softfp' floating
+ point models.
+
+ If your processor has a floating point unit, and you don't
+ depend on existing pre-compiled code, this option is most
+ likely the best choice.
+
+endchoice
config BR2_ARM_ENABLE_NEON
bool "Enable NEON SIMD extension support"
Select this option if you are certain your particular
implementation has NEON support and you want to use it.
+choice
+ prompt "Floating point strategy"
+ depends on BR2_ARM_EABI || BR2_ARM_EABIHF
+ default BR2_ARM_FPU_VFPV4D16 if BR2_ARM_CPU_HAS_VFPV4
+ default BR2_ARM_FPU_VFPV3D16 if BR2_ARM_CPU_HAS_VFPV3
+ default BR2_ARM_FPU_VFPV2 if BR2_ARM_CPU_HAS_VFPV2
+ default BR2_ARM_SOFT_FLOAT if !BR2_ARM_CPU_HAS_VFPV2
+
+config BR2_ARM_SOFT_FLOAT
+ bool "Soft float"
+ depends on BR2_ARM_EABI
+ select BR2_SOFT_FLOAT
+ help
+ This option allows to use software emulated floating
+ point. It should be used for ARM cores that do not include a
+ Vector Floating Point unit, such as ARMv5 cores (ARM926 for
+ example) or certain ARMv6 cores.
+
+config BR2_ARM_FPU_VFPV2
+ bool "VFPv2"
+ depends on BR2_ARM_CPU_HAS_VFPV2 || BR2_ARM_CPU_MAYBE_HAS_VFPV2
+ help
+ This option allows to use the VFPv2 floating point unit, as
+ available in some ARMv6 processors (ARM1136JF-S,
+ ARM1176JZF-S and ARM11 MPCore).
+
+ Note that this option is also safe to use for newer cores
+ such as Cortex-A, because the VFPv3 and VFPv4 units are
+ backward compatible with VFPv2.
+
+config BR2_ARM_FPU_VFPV3
+ bool "VFPv3"
+ depends on BR2_ARM_CPU_HAS_VFPV3 || BR2_ARM_CPU_MAYBE_HAS_VFPV3
+ help
+ This option allows to use the VFPv3 floating point unit, as
+ available in some ARMv7 processors (Cortex-A{8, 9}). This
+ option requires a VFPv3 unit that has 32 double-precision
+ registers, which is not necessarily the case in all SOCs
+ based on Cortex-A{8, 9}. If you're unsure, use VFPv3-D16
+ instead, which is guaranteed to work on all Cortex-A{8, 9}.
+
+ Note that this option is also safe to use for newer cores
+ that have a VFPv4 unit, because VFPv4 is backward compatible
+ with VFPv3. They must of course also have 32
+ double-precision registers.
+
+config BR2_ARM_FPU_VFPV3D16
+ bool "VFPv3-D16"
+ depends on BR2_ARM_CPU_HAS_VFPV3 || BR2_ARM_CPU_MAYBE_HAS_VFPV3
+ help
+ This option allows to use the VFPv3 floating point unit, as
+ available in some ARMv7 processors (Cortex-A{8, 9}). This
+ option requires a VFPv3 unit that has 16 double-precision
+ registers, which is generally the case in all SOCs based on
+ Cortex-A{8, 9}, even though VFPv3 is technically optional on
+ Cortex-A9. This is the safest option for those cores.
+
+ Note that this option is also safe to use for newer cores
+ such that have a VFPv4 unit, because the VFPv4 is backward
+ compatible with VFPv3.
+
+config BR2_ARM_FPU_VFPV4
+ bool "VFPv4"
+ depends on BR2_ARM_CPU_HAS_VFPV4 || BR2_ARM_CPU_MAYBE_HAS_VFPV4
+ help
+ This option allows to use the VFPv4 floating point unit, as
+ available in some ARMv7 processors (Cortex-A{5, 7, 12,
+ 15}). This option requires a VFPv4 unit that has 32
+ double-precision registers, which is not necessarily the
+ case in all SOCs based on Cortex-A{5, 7, 12, 15}. If you're
+ unsure, you should probably use VFPv4-D16 instead.
+
+ Note that if you want binary code that works on all ARMv7
+ cores, including the earlier Cortex-A{8, 9}, you should
+ instead select VFPv3.
+
+config BR2_ARM_FPU_VFPV4D16
+ bool "VFPv4-D16"
+ depends on BR2_ARM_CPU_HAS_VFPV4 || BR2_ARM_CPU_MAYBE_HAS_VFPV4
+ help
+ This option allows to use the VFPv4 floating point unit, as
+ available in some ARMv7 processors (Cortex-A{5, 7, 12,
+ 15}). This option requires a VFPv4 unit that has 16
+ double-precision registers, which is always available on
+ Cortex-A12 and Cortex-A15, but optional on Cortex-A5 and
+ Cortex-A7.
+
+ Note that if you want binary code that works on all ARMv7
+ cores, including the earlier Cortex-A{8, 9}, you should
+ instead select VFPv3-D16.
+
+config BR2_ARM_FPU_NEON
+ bool "NEON"
+ depends on BR2_ARM_CPU_HAS_NEON
+ help
+ This option allows to use the NEON SIMD unit, as available
+ in some ARMv7 processors, as a floating-point unit. It
+ should however be noted that using NEON for floating point
+ operations doesn't provide a complete compatibility with the
+ IEEE 754.
+
+config BR2_ARM_FPU_NEON_VFPV4
+ bool "NEON/VFPv4"
+ depends on BR2_ARM_CPU_HAS_VFPV4 || BR2_ARM_CPU_MAYBE_HAS_VFPV4
+ depends on BR2_ARM_CPU_HAS_NEON
+ help
+ This option allows to use both the VFPv4 and the NEON SIMD
+ units for floating point operations. Note that some ARMv7
+ cores do not necessarily have VFPv4 and/or NEON support, for
+ example on Cortex-A5 and Cortex-A7, support for VFPv4 and
+ NEON is optional.
+
+endchoice
+
config BR2_ARCH
default "arm" if BR2_arm
default "armeb" if BR2_armeb
config BR2_GCC_TARGET_ABI
default "aapcs-linux"
+
+config BR2_GCC_TARGET_FPU
+ default "vfp" if BR2_ARM_FPU_VFPV2
+ default "vfpv3" if BR2_ARM_FPU_VFPV3
+ default "vfpv3-d16" if BR2_ARM_FPU_VFPV3D16
+ default "vfpv4" if BR2_ARM_FPU_VFPV4
+ default "vfpv4-d16" if BR2_ARM_FPU_VFPV4D16
+ default "neon" if BR2_ARM_FPU_NEON
+ default "neon-vfpv4" if BR2_ARM_FPU_NEON_VFPV4
+
+config BR2_GCC_TARGET_FLOAT_ABI
+ default "soft" if BR2_ARM_SOFT_FLOAT
+ default "softfp" if !BR2_ARM_SOFT_FLOAT && BR2_ARM_EABI
+ default "hard" if !BR2_ARM_SOFT_FLOAT && BR2_ARM_EABIHF
projects / buildroot.git / commitdiff