[PATCH 2/4] riscv: Add support for kexec handover (KHO)

[Chen Pei <cp0613@linux.alibaba.com>]

KHO is architecture independent: the outgoing kernel publishes the
handover FDT and the scratch descriptor array in the /chosen node of
the DTB it builds for the incoming kernel (kho_add_chosen(), reached
from of_kexec_alloc_and_setup_fdt()), and the incoming kernel picks
both up while scanning that node (early_init_dt_check_kho() ->
kho_populate()).

RISC-V already builds that DTB in load_extra_segments() and passes it
to the incoming kernel in a1, so only the architecture symbol is
missing.  Depend on 64BIT to match ARCH_SUPPORTS_KEXEC_FILE, and on
MMU because KEXEC_HANDOVER selects CMA, which depends on MMU.

Signed-off-by: Chen Pei <cp0613@linux.alibaba.com>
---
 arch/riscv/Kconfig | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 5874ca30f4f6..4f7d2f3f80b1 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -1125,6 +1125,9 @@ config ARCH_SELECTS_KEXEC_FILE
 config ARCH_SUPPORTS_KEXEC_PURGATORY
 	def_bool ARCH_SUPPORTS_KEXEC_FILE
 
+config ARCH_SUPPORTS_KEXEC_HANDOVER
+	def_bool 64BIT && MMU
+
 config ARCH_SUPPORTS_CRASH_DUMP
 	def_bool y
 
-- 
2.50.1