Re: [PATCH v3] RISC-V: Add CONFIG_{NON,}PORTABLE
From: Palmer Dabbelt
Date: Thu Jul 14 2022 - 17:26:18 EST
On Sat, 21 May 2022 12:33:57 PDT (-0700), Palmer Dabbelt wrote:
From: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
The RISC-V port has collected a handful of options that are
fundamentally non-portable. To prevent users from shooting themselves
in the foot, hide them all behind a config entry that explicitly calls
out that non-portable binaries may be produced.
Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
---
Changes since v2:
* Update the nommu and rv32 defconfigs. I'm still getting some ugliness
like
$ make.riscv rv32_defconfig
*** Default configuration is based on 'defconfig'
#
# configuration written to .config
#
Using .config as base
Merging ./arch/riscv/configs/32-bit.config
Value of CONFIG_PORTABLE is redefined by fragment ./arch/riscv/configs/32-bit.config:
Previous value: CONFIG_PORTABLE=y
New value: # CONFIG_PORTABLE is not set
Value of CONFIG_NONPORTABLE is redefined by fragment ./arch/riscv/configs/32-bit.config:
Previous value: # CONFIG_NONPORTABLE is not set
New value: CONFIG_NONPORTABLE=y
#
# merged configuration written to .config (needs make)
#
.config:3831:warning: override: ARCH_RV32I changes choice state
#
# configuration written to .config
#
not sure if there's a better way to do this.
Changes since v1:
* Fix a bunch of spelling mistakes.
* Move NONPORTABLE under the "Platform type" sub-heading.
* Fix the rv32i dependency.
---
arch/riscv/Kconfig | 28 +++++++++++++++++--
arch/riscv/configs/32-bit.config | 2 ++
arch/riscv/configs/nommu_k210_defconfig | 1 +
.../riscv/configs/nommu_k210_sdcard_defconfig | 1 +
arch/riscv/configs/nommu_virt_defconfig | 1 +
arch/riscv/configs/rv32_defconfig | 1 +
6 files changed, 32 insertions(+), 2 deletions(-)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index f863065b478c..cd67b09a80f5 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -222,6 +222,21 @@ source "arch/riscv/Kconfig.erratas"
menu "Platform type"
+config NONPORTABLE
+ bool "Allow configurations that result in non-portable kernels"
+ help
+ RISC-V kernel binaries are compatible between all known systems
+ whenever possible, but there are some use cases that can only be
+ satisfied by configurations that result in kernel binaries that are
+ not portable between systems.
+
+ Selecting N does not guarantee kernels will be portable to all known
+ systems. Selecting any of the options guarded by NONPORTABLE will
+ result in kernel binaries that are unlikely to be portable between
+ systems.
+
+ If unsure, say N.
+
choice
prompt "Base ISA"
default ARCH_RV64I
@@ -231,6 +246,7 @@ choice
config ARCH_RV32I
bool "RV32I"
+ depends on NONPORTABLE
select 32BIT
select GENERIC_LIB_ASHLDI3
select GENERIC_LIB_ASHRDI3
@@ -541,6 +557,7 @@ config STACKPROTECTOR_PER_TASK
config PHYS_RAM_BASE_FIXED
bool "Explicitly specified physical RAM address"
+ depends on NONPORTABLE
default n
config PHYS_RAM_BASE
@@ -554,7 +571,7 @@ config PHYS_RAM_BASE
config XIP_KERNEL
bool "Kernel Execute-In-Place from ROM"
- depends on MMU && SPARSEMEM
+ depends on MMU && SPARSEMEM && NONPORTABLE
# This prevents XIP from being enabled by all{yes,mod}config, which
# fail to build since XIP doesn't support large kernels.
depends on !COMPILE_TEST
@@ -594,9 +611,16 @@ endmenu
config BUILTIN_DTB
bool
- depends on OF
+ depends on OF && NONPORTABLE
default y if XIP_KERNEL
+config PORTABLE
+ bool
+ default !NONPORTABLE
+ select EFI
+ select OF
+ select MMU
+
menu "Power management options"
source "kernel/power/Kconfig"
diff --git a/arch/riscv/configs/32-bit.config b/arch/riscv/configs/32-bit.config
index 43f41323b67e..f6af0f708df4 100644
--- a/arch/riscv/configs/32-bit.config
+++ b/arch/riscv/configs/32-bit.config
@@ -1,2 +1,4 @@
CONFIG_ARCH_RV32I=y
CONFIG_32BIT=y
+# CONFIG_PORTABLE is not set
+CONFIG_NONPORTABLE=y
diff --git a/arch/riscv/configs/nommu_k210_defconfig b/arch/riscv/configs/nommu_k210_defconfig
index 2438fa39f8ae..96fe8def644c 100644
--- a/arch/riscv/configs/nommu_k210_defconfig
+++ b/arch/riscv/configs/nommu_k210_defconfig
@@ -28,6 +28,7 @@ CONFIG_EMBEDDED=y
CONFIG_SLOB=y
# CONFIG_MMU is not set
CONFIG_SOC_CANAAN=y
+CONFIG_NONPORTABLE=y
CONFIG_SMP=y
CONFIG_NR_CPUS=2
CONFIG_CMDLINE="earlycon console=ttySIF0"
diff --git a/arch/riscv/configs/nommu_k210_sdcard_defconfig b/arch/riscv/configs/nommu_k210_sdcard_defconfig
index 9a133e63ae5b..379740654373 100644
--- a/arch/riscv/configs/nommu_k210_sdcard_defconfig
+++ b/arch/riscv/configs/nommu_k210_sdcard_defconfig
@@ -20,6 +20,7 @@ CONFIG_EMBEDDED=y
CONFIG_SLOB=y
# CONFIG_MMU is not set
CONFIG_SOC_CANAAN=y
+CONFIG_NONPORTABLE=y
CONFIG_SMP=y
CONFIG_NR_CPUS=2
CONFIG_CMDLINE="earlycon console=ttySIF0 root=/dev/mmcblk0p1 rootwait ro"
diff --git a/arch/riscv/configs/nommu_virt_defconfig b/arch/riscv/configs/nommu_virt_defconfig
index 5269fbb6b4fc..1a56eda5ce46 100644
--- a/arch/riscv/configs/nommu_virt_defconfig
+++ b/arch/riscv/configs/nommu_virt_defconfig
@@ -25,6 +25,7 @@ CONFIG_EXPERT=y
CONFIG_SLOB=y
# CONFIG_MMU is not set
CONFIG_SOC_VIRT=y
+CONFIG_NONPORTABLE=y
CONFIG_SMP=y
CONFIG_CMDLINE="root=/dev/vda rw earlycon=uart8250,mmio,0x10000000,115200n8 console=ttyS0"
CONFIG_CMDLINE_FORCE=y
diff --git a/arch/riscv/configs/rv32_defconfig b/arch/riscv/configs/rv32_defconfig
index 7e5efdc3829d..77bdb1d05a88 100644
--- a/arch/riscv/configs/rv32_defconfig
+++ b/arch/riscv/configs/rv32_defconfig
@@ -18,6 +18,7 @@ CONFIG_EXPERT=y
CONFIG_PROFILING=y
CONFIG_SOC_SIFIVE=y
CONFIG_SOC_VIRT=y
+CONFIG_NONPORTABLE=y
CONFIG_ARCH_RV32I=y
CONFIG_SMP=y
CONFIG_HOTPLUG_CPU=y
This is on for-next.