[PATCH 4/4] riscv: Allow NOMMU kernels to run in S-mode
Samuel Holland
samuel.holland at sifive.com
Mon Feb 26 16:34:49 PST 2024
For ease of testing, it is convenient to run NOMMU kernels in supervisor
mode. The only required change is to offset the kernel load address,
since the beginning of RAM is usually reserved for M-mode firmware.
Signed-off-by: Samuel Holland <samuel.holland at sifive.com>
---
arch/riscv/Kconfig | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index ef53c00470d6..0dc09b2ac2f6 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -64,7 +64,7 @@ config RISCV
select ARCH_WANTS_THP_SWAP if HAVE_ARCH_TRANSPARENT_HUGEPAGE
select BINFMT_FLAT_NO_DATA_START_OFFSET if !MMU
select BUILDTIME_TABLE_SORT if MMU
- select CLINT_TIMER if !MMU
+ select CLINT_TIMER if RISCV_M_MODE
select CLONE_BACKWARDS
select COMMON_CLK
select CPU_PM if CPU_IDLE || HIBERNATION || SUSPEND
@@ -220,8 +220,12 @@ config ARCH_MMAP_RND_COMPAT_BITS_MAX
# set if we run in machine mode, cleared if we run in supervisor mode
config RISCV_M_MODE
- bool
- default !MMU
+ bool "Build a kernel that runs in machine mode"
+ depends on !MMU
+ default y
+ help
+ Select this option if you want to run the kernel in M-mode,
+ without the assistance of any other firmware.
# set if we are running in S-mode and can use SBI calls
config RISCV_SBI
@@ -238,8 +242,9 @@ config MMU
config PAGE_OFFSET
hex
- default 0xC0000000 if 32BIT && MMU
- default 0x80000000 if !MMU
+ default 0x80000000 if !MMU && RISCV_M_MODE
+ default 0x80200000 if !MMU
+ default 0xc0000000 if 32BIT
default 0xff60000000000000 if 64BIT
config KASAN_SHADOW_OFFSET
--
2.43.0
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