91 lines
3.6 KiB
Go
91 lines
3.6 KiB
Go
package buildinfo
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import (
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"runtime"
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"golang.org/x/sys/cpu"
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)
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// GetSupportedGOARM returns the ARM compatibility level of the current CPU.
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//
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// Returns the integer value that can be set for the GOARM variable to
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// build with this level as target, a value which normally corresponds to the
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// ARM architecture version number, although it is the floating point hardware
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// support which is the decicive factor.
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//
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// Only relevant for 32-bit ARM architectures, where GOARCH=arm, which means
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// ARMv7 and lower (ARMv8 is GOARCH=arm64 and GOARM is not considered).
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// Highest possible value is therefore 7, while other possible values are
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// 6 (for ARMv6) and 5 (for ARMv5, which is the lowest currently supported
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// in go. Returns value 0 for anything else.
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//
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// See also:
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//
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// https://go.dev/src/runtime/os_linux_arm.go
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// https://github.com/golang/go/wiki/GoArm
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func GetSupportedGOARM() int {
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if runtime.GOARCH == "arm" && cpu.Initialized {
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// This CPU is an ARM (32-bit), and cpu.Initialized true means its
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// features could be retrieved on current GOOS so that we can check
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// for floating point hardware support.
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if cpu.ARM.HasVFPv3 {
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// This CPU has VFPv3 floating point hardware, which means it can
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// run programs built with any GOARM value, 7 and lower.
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return 7
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} else if cpu.ARM.HasVFP {
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// This CPU has VFP floating point hardware, but not VFPv3, which
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// means it can run programs built with GOARM value 6 and lower,
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// but not 7.
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return 6
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}
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// This CPU has no VFP floating point hardware, which means it can
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// only run programs built with GOARM value 5, which is minimum supported.
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// Note that the CPU can still in reality be based on e.g. ARMv7
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// architecture, but simply lack hardfloat support.
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return 5
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}
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return 0
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}
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// GetArch tells the rclone executable's architecture target.
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func GetArch() string {
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// Get the running program's architecture target.
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arch := runtime.GOARCH
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// For ARM architectures there are several variants, with different
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// inconsistent and ambiguous naming.
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//
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// The most interesting thing here is which compatibility level of go is
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// used, as controlled by GOARM build variable. We cannot in runtime get
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// the actual value of GOARM used for building this program, but we can
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// check the value supported by the current CPU by calling GetSupportedGOARM.
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// This means we return information about the compatibility level (GOARM
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// value) supported, when the current rclone executable may in reality be
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// built with a lower level.
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//
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// Note that the kernel architecture, as returned by "uname -m", is not
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// considered or included in results here, but it is included in the output
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// from function GetOSVersion. It can have values such as armv6l, armv7l,
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// armv8l, arm64 and aarch64, which may give relevant information. But it
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// can also simply have value "arm", or it can have value "armv7l" for a
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// processor based on ARMv7 but without floating point hardware - which
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// means it in go needs to be built in ARMv5 compatibility mode (GOARM=5).
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if arch == "arm64" {
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// 64-bit ARM architecture, known as AArch64, was introduced with ARMv8.
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// In go this architecture is a specific one, separate from other ARMs.
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arch += " (ARMv8 compatible)"
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} else if arch == "arm" {
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// 32-bit ARM architecture, which is ARMv7 and lower.
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// In go there are different compatibility levels represented by ARM
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// architecture version number (like 5, 6 or 7).
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switch GetSupportedGOARM() {
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case 7:
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arch += " (ARMv7 compatible)"
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case 6:
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arch += " (ARMv6 compatible)"
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case 5:
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arch += " (ARMv5 compatible, no hardfloat)"
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}
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}
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return arch
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}
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