[PATCH 0/4] ARM: get a strict multiplatform kernel that can run on any hardware

[PATCH 0/4] ARM: get a strict multiplatform kernel that can run on any hardware

[Xia Kaixu]

The current allmodconfig kernel boot fails on OMAP4460. There
are several configuration options that can only work on a subset
of the available machines, and enabling them will break other
machines that may be enabled in a multiplatform kernel.

Now we introduce a CONFIG_ARCH_MULTIPLATFORM_STRICT Kconfig 
option that prevent those other options from getting enabled
and get a strict multiplatform kernel.

This patch set is not complete yet(missing the console).

I am not sure who will pick up this patch set, so I just send 
it to arm at kernel.org and rmk.

Xia Kaixu (4):
  ARM: introduce a CONFIG_ARCH_MULTIPLATFORM_STRICT Kconfig option
  ARM: change the corresponding arm/mach defconfigs
  ARM: restrict CPU_BIG_ENDIAN configuration option
  ARM: allow errata and XIP options to be enabled without ARCH_MULTIPLATFORM_STRICT

 arch/arm/Kconfig                   | 28 +++++++++++++++++++++-------
 arch/arm/configs/bcm2835_defconfig |  1 +
 arch/arm/configs/moxart_defconfig  |  1 +
 arch/arm/configs/s5pv210_defconfig |  1 +
 arch/arm/configs/tegra_defconfig   |  1 +
 arch/arm/mm/Kconfig                |  1 +
 6 files changed, 26 insertions(+), 7 deletions(-)

-- 
2.1.1

[PATCH 1/4] ARM: introduce a CONFIG_ARCH_MULTIPLATFORM_STRICT Kconfig option

[Xia Kaixu]

The current allmodconfig kernel boot fails on OMAP4460. There
are several configuration options that can only work on a subset
of the available machines, and enabling them will break other
machines that may be enabled in a multiplatform kernel.

Now we introduce a CONFIG_ARCH_MULTIPLATFORM_STRICT Kconfig 
option that prevent those other options from getting enabled
and get a strict multiplatform kernel.

Signed-off-by: Xia Kaixu <kaixu.xia@linaro.org>
---
 arch/arm/Kconfig | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 89c4b5c..50762cc 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -840,6 +840,20 @@ config ARCH_MULTI_CPU_AUTO
 
 endmenu
 
+config ARCH_MULTIPLATFORM_STRICT
+	bool "Only allow options that do not break other platforms"
+	depends on ARCH_MULTIPLATFORM
+	default y
+	help
+         There are several configuration options that can only work
+         on a subset of the available machines, and enabling them
+         will break running the kernel on other machines that may be
+         enabled in a multiplatform kernel.
+
+         Enabling ARCH_MULTIPLATFORM_STRICT will prevent those other
+         options from getting enabled, so the kernel should always
+         run on any hardware that is part of the configuration.
+
 config ARCH_VIRT
 	bool "Dummy Virtual Machine" if ARCH_MULTI_V7
 	select ARM_AMBA
-- 
2.1.1

[PATCH 2/4] ARM: change the corresponding arm/mach defconfigs

[Xia Kaixu]

The DEBUG_LL will get a dependency on !ARCH_MULTIPLATFORM_STRICT.
So change the corresponding arm/mach defconfigs to disable 
ARCH_MULTIPLATFORM_STRICT and avoid break them.

Signed-off-by: Xia Kaixu <kaixu.xia@linaro.org>
---
 arch/arm/configs/bcm2835_defconfig | 1 +
 arch/arm/configs/moxart_defconfig  | 1 +
 arch/arm/configs/s5pv210_defconfig | 1 +
 arch/arm/configs/tegra_defconfig   | 1 +
 4 files changed, 4 insertions(+)

diff --git a/arch/arm/configs/bcm2835_defconfig b/arch/arm/configs/bcm2835_defconfig
index 31cb073..e644c8b 100644
--- a/arch/arm/configs/bcm2835_defconfig
+++ b/arch/arm/configs/bcm2835_defconfig
@@ -135,6 +135,7 @@ CONFIG_TEST_KSTRTOX=y
 CONFIG_KGDB=y
 CONFIG_KGDB_KDB=y
 CONFIG_STRICT_DEVMEM=y
+# CONFIG_ARCH_MULTIPLATFORM_STRICT is not set
 CONFIG_DEBUG_LL=y
 CONFIG_EARLY_PRINTK=y
 # CONFIG_XZ_DEC_ARM is not set
diff --git a/arch/arm/configs/moxart_defconfig b/arch/arm/configs/moxart_defconfig
index a3cb76c..7ba9343 100644
--- a/arch/arm/configs/moxart_defconfig
+++ b/arch/arm/configs/moxart_defconfig
@@ -140,6 +140,7 @@ CONFIG_DETECT_HUNG_TASK=y
 CONFIG_PROVE_LOCKING=y
 CONFIG_DMA_API_DEBUG=y
 CONFIG_KGDB=y
+# CONFIG_ARCH_MULTIPLATFORM_STRICT is not set
 CONFIG_DEBUG_LL=y
 CONFIG_DEBUG_LL_UART_8250=y
 CONFIG_DEBUG_UART_PHYS=0x98200000
diff --git a/arch/arm/configs/s5pv210_defconfig b/arch/arm/configs/s5pv210_defconfig
index fa98990..bc0cad4 100644
--- a/arch/arm/configs/s5pv210_defconfig
+++ b/arch/arm/configs/s5pv210_defconfig
@@ -67,6 +67,7 @@ CONFIG_DEBUG_INFO=y
 CONFIG_SYSCTL_SYSCALL_CHECK=y
 CONFIG_DEBUG_USER=y
 CONFIG_DEBUG_ERRORS=y
+# CONFIG_ARCH_MULTIPLATFORM_STRICT is not set
 CONFIG_DEBUG_LL=y
 CONFIG_EARLY_PRINTK=y
 CONFIG_DEBUG_S3C_UART=1
diff --git a/arch/arm/configs/tegra_defconfig b/arch/arm/configs/tegra_defconfig
index 888fc15..851b80b 100644
--- a/arch/arm/configs/tegra_defconfig
+++ b/arch/arm/configs/tegra_defconfig
@@ -291,6 +291,7 @@ CONFIG_TIMER_STATS=y
 # CONFIG_DEBUG_PREEMPT is not set
 CONFIG_DEBUG_MUTEXES=y
 CONFIG_DEBUG_SG=y
+# CONFIG_ARCH_MULTIPLATFORM_STRICT is not set
 CONFIG_DEBUG_LL=y
 CONFIG_EARLY_PRINTK=y
 CONFIG_CRYPTO_TWOFISH=y
-- 
2.1.1

[PATCH 3/4] ARM: restrict CPU_BIG_ENDIAN configuration option

[Xia Kaixu]

Some platforms don't work when CPU_BIG_ENDIAN is enabled.
So It can get a dependency on !ARCH_MULTIPLATFORM_STRICT.

Signed-off-by: Xia Kaixu <kaixu.xia@linaro.org>
---
 arch/arm/mm/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index ae69809..d510448 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -698,6 +698,7 @@ config SWP_EMULATE
 config CPU_BIG_ENDIAN
 	bool "Build big-endian kernel"
 	depends on ARCH_SUPPORTS_BIG_ENDIAN
+	depends on !ARCH_MULTIPLATFORM_STRICT
 	help
 	  Say Y if you plan on running a kernel in big-endian mode.
 	  Note that your board must be properly built and your board
-- 
2.1.1

[PATCH 4/4] ARM: allow errata and XIP options to be enabled without ARCH_MULTIPLATFORM_STRICT

[Xia Kaixu]

With the ARCH_MULTIPLATFORM_STRICT option, it becomes much easier to 
enable the ERRATA options when we know at configuration time that we
don't care about the generic case. The previous configuration makes
XIP_KERNEL option fundamentally non-MULTIPLATFORM, but it's still
valid to select it when building for !ARCH_MULTIPLATFORM_STRICT and
selecting only the one machine that you want to run on.

So allow ARM_ERRATA and XIP_KERNEL options to be enabled without
ARCH_MULTIPLATFORM_STRICT.

Signed-off-by: Xia Kaixu <kaixu.xia@linaro.org>
---
 arch/arm/Kconfig | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 50762cc..14d0dce 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1091,7 +1091,7 @@ config ARM_ERRATA_430973
 config ARM_ERRATA_458693
 	bool "ARM errata: Processor deadlock when a false hazard is created"
 	depends on CPU_V7
-	depends on !ARCH_MULTIPLATFORM
+	depends on !ARCH_MULTIPLATFORM_STRICT
 	help
 	  This option enables the workaround for the 458693 Cortex-A8 (r2p0)
 	  erratum. For very specific sequences of memory operations, it is
@@ -1105,7 +1105,7 @@ config ARM_ERRATA_458693
 config ARM_ERRATA_460075
 	bool "ARM errata: Data written to the L2 cache can be overwritten with stale data"
 	depends on CPU_V7
-	depends on !ARCH_MULTIPLATFORM
+	depends on !ARCH_MULTIPLATFORM_STRICT
 	help
 	  This option enables the workaround for the 460075 Cortex-A8 (r2p0)
 	  erratum. Any asynchronous access to the L2 cache may encounter a
@@ -1118,7 +1118,7 @@ config ARM_ERRATA_460075
 config ARM_ERRATA_742230
 	bool "ARM errata: DMB operation may be faulty"
 	depends on CPU_V7 && SMP
-	depends on !ARCH_MULTIPLATFORM
+	depends on !ARCH_MULTIPLATFORM_STRICT
 	help
 	  This option enables the workaround for the 742230 Cortex-A9
 	  (r1p0..r2p2) erratum. Under rare circumstances, a DMB instruction
@@ -1131,7 +1131,7 @@ config ARM_ERRATA_742230
 config ARM_ERRATA_742231
 	bool "ARM errata: Incorrect hazard handling in the SCU may lead to data corruption"
 	depends on CPU_V7 && SMP
-	depends on !ARCH_MULTIPLATFORM
+	depends on !ARCH_MULTIPLATFORM_STRICT
 	help
 	  This option enables the workaround for the 742231 Cortex-A9
 	  (r2p0..r2p2) erratum. Under certain conditions, specific to the
@@ -1168,7 +1168,7 @@ config ARM_ERRATA_720789
 config ARM_ERRATA_743622
 	bool "ARM errata: Faulty hazard checking in the Store Buffer may lead to data corruption"
 	depends on CPU_V7
-	depends on !ARCH_MULTIPLATFORM
+	depends on !ARCH_MULTIPLATFORM_STRICT
 	help
 	  This option enables the workaround for the 743622 Cortex-A9
 	  (r2p*) erratum. Under very rare conditions, a faulty
@@ -1182,7 +1182,7 @@ config ARM_ERRATA_743622
 config ARM_ERRATA_751472
 	bool "ARM errata: Interrupted ICIALLUIS may prevent completion of broadcasted operation"
 	depends on CPU_V7
-	depends on !ARCH_MULTIPLATFORM
+	depends on !ARCH_MULTIPLATFORM_STRICT
 	help
 	  This option enables the workaround for the 751472 Cortex-A9 (prior
 	  to r3p0) erratum. An interrupted ICIALLUIS operation may prevent the
@@ -1987,7 +1987,7 @@ endchoice
 
 config XIP_KERNEL
 	bool "Kernel Execute-In-Place from ROM"
-	depends on !ARM_LPAE && !ARCH_MULTIPLATFORM
+	depends on !ARM_LPAE && !ARCH_MULTIPLATFORM_STRICT
 	help
 	  Execute-In-Place allows the kernel to run from non-volatile storage
 	  directly addressable by the CPU, such as NOR flash. This saves RAM
-- 
2.1.1