Unverified Commit 77d707a3 authored by Palmer Dabbelt's avatar Palmer Dabbelt
Browse files

RISC-V: Only default to spinwait on SBI-0.1 and M-mode 



The spinwait boot method has been superseded by the SBI HSM extension
for some time now, but it still enabled by default.  This causes some
issues on large hart count systems, which will hang if a physical hart
exists that is larger than NR_CPUS.

Users on modern SBI implementation don't need spinwait, and while it's
probably possible to deal with some of the spinwait issues let's just
restrict the default to systems that are likely to actually use it.

Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
Reviewed-by: default avatarAtish Patra <atishp@rivosinc.com>
Reviewed-by: default avatarAnup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20220421170354.10555-1-palmer@rivosinc.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 2981deb8

arch/riscv/Kconfig

+7 −1
Original line number Diff line number Diff line
@@ -396,7 +396,7 @@ config RISCV_SBI_V01 
config RISCV_BOOT_SPINWAIT

	bool "Spinwait booting method"

	depends on SMP

	default y

	default y if RISCV_SBI_V01 || RISCV_M_MODE

	help

	  This enables support for booting Linux via spinwait method. In the

	  spinwait method, all cores randomly jump to Linux. One of the cores
@@ -407,6 +407,12 @@ config RISCV_BOOT_SPINWAIT 
	  rely on ordered booting via SBI HSM extension which gets chosen

	  dynamically at runtime if the firmware supports it.



	  Since spinwait is incompatible with sparse hart IDs, it requires

	  NR_CPUS be large enough to contain the physical hart ID of the first

	  hart to enter Linux.



	  If unsure what to do here, say N.



config KEXEC

	bool "Kexec system call"

	select KEXEC_CORE