Add a RISCV64 variable to cpu that indicates both the presence
of RISC-V extensions and performance information about the underlying
RISC-V cores. The variable is only populated with non false values on
Linux. The detection code first attempts to use the riscv_hwprobe
syscall introduced in Linux 6.4, falling back to HWCAP if riscv_hwprobe
is not supported. The patch can detect the C, V, Zba, Zbb and Zbs
extensions. V, Zba, Zbb and Zbs can only be detected on a 6.5 kernel
or later (without backports).
Updates golang/go#61416
Change-Id: I40f92724ee3d337c06bdc559ff0b18a8f6bfda9f
Reviewed-on: https://go-review.googlesource.com/c/sys/+/605815
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Joel Sing <joel@sing.id.au>
Reviewed-by: Meng Zhuo <mengzhuo1203@gmail.com>
The riscv_hwprobe system call was introduced in Linux 6.4 and allows
the caller to determine a number of interesting pieces of information
about the underlying RISC-V CPUs, e.g., which extensions they support
and whether they allow fast unaligned memory accesses. For more information
please see:
https://docs.kernel.org/riscv/hwprobe.html
We also update linux/mksysnum.go to ensure that the generated syscall constants
written to the zsysnum_linux_*.go files are always sorted by their syscall numbers
in ascending order.
Updates golang/go#61416
Change-Id: Iedb0a86adb65faac9061b9a5969ffa09eb5b303a
Reviewed-on: https://go-review.googlesource.com/c/sys/+/510795
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Mark Ryan