riscv: Allow to enable PREEMPT_RT.

It is really time.

riscv has all the required architecture related changes, that have been
identified over time, in order to enable PREEMPT_RT. With the recent
printk changes, the last known road block has been addressed.

Allow to enable PREEMPT_RT on riscv.

Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Tested-by: Nam Cao <[email protected]> # Visionfive 2
Link: https://lore.kernel.org/all/[email protected]

Author: Sebastian Andrzej Siewior

arch/riscv/Kconfig

@@ -65,6 +65,7 @@ config RISCV
 	select ARCH_SUPPORTS_LTO_CLANG_THIN if LLD_VERSION >= 140000
 	select ARCH_SUPPORTS_PAGE_TABLE_CHECK if MMU
 	select ARCH_SUPPORTS_PER_VMA_LOCK if MMU
+	select ARCH_SUPPORTS_RT
 	select ARCH_SUPPORTS_SHADOW_CALL_STACK if HAVE_SHADOW_CALL_STACK
 	select ARCH_USE_CMPXCHG_LOCKREF if 64BIT
 	select ARCH_USE_MEMTEST