ARM: split out ATAGS parsing

PATCH New Nicolas Pitre 5 participants 9 messages Aug 30, 2012 – Sep 5, 2012 Arm (32-bit)

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Nicolas Pitre

author

2012-08-30 21:10 UTC #0 lore raw

PATCH 1/2 ARM: split out ATAGS parsing

Make ATAGS parsing into a source file of its own, namely atags_parse.c. Also rename compat.c to atags_compat.c to make it clearer what it is about. Same for atags.c which is now atags_proc.c. Gather all the atags function declarations into a common atags.h.

Signed-off-by Nicolas Pitre <[email protected]>

---
 arch/arm/kernel/Makefile                     |   6 +-
 arch/arm/kernel/atags.h                      |   3 +
 arch/arm/kernel/{compat.c => atags_compat.c} |   4 +-
 arch/arm/kernel/atags_parse.c                | 238 +++++++++++++++++++++++++++
 arch/arm/kernel/{atags.c => atags_proc.c}    |   0
 arch/arm/kernel/compat.h                     |  11 --
 arch/arm/kernel/setup.c                      | 236 +-------------------------
 7 files changed, 247 insertions(+), 251 deletions(-)
 rename arch/arm/kernel/{compat.c => atags_compat.c} (99%)
 create mode 100644 arch/arm/kernel/atags_parse.c
 rename arch/arm/kernel/{atags.c => atags_proc.c} (100%)
 delete mode 100644 arch/arm/kernel/compat.h

arch/arm/kernel/Makefile +3 -3

index 7ad2d5cf70..086c9d3bc3 100644
@@ -15,11 +15,11 @@ CFLAGS_REMOVE_return_address.o = -pg
 
 # Object file lists.
 
-obj-y		:= elf.o entry-armv.o entry-common.o irq.o opcodes.o \
+obj-y		:= atags_parse.o elf.o entry-armv.o entry-common.o irq.o opcodes.o \
 		   process.o ptrace.o return_address.o sched_clock.o \
 		   setup.o signal.o stacktrace.o sys_arm.o time.o traps.o
 
-obj-$(CONFIG_DEPRECATED_PARAM_STRUCT) += compat.o
+obj-$(CONFIG_DEPRECATED_PARAM_STRUCT) += atags_compat.o
 
 obj-$(CONFIG_LEDS)		+= leds.o
 obj-$(CONFIG_OC_ETM)		+= etm.o

@@ -52,7 +52,7 @@ test-kprobes-objs		+= kprobes-test-thumb.o
 else
 test-kprobes-objs		+= kprobes-test-arm.o
 endif
-obj-$(CONFIG_ATAGS_PROC)	+= atags.o
+obj-$(CONFIG_ATAGS_PROC)	+= atags_proc.o
 obj-$(CONFIG_OABI_COMPAT)	+= sys_oabi-compat.o
 obj-$(CONFIG_ARM_THUMBEE)	+= thumbee.o
 obj-$(CONFIG_KGDB)		+= kgdb.o

arch/arm/kernel/atags.h +3 -0

index e5f028d214..a888fdd381 100644
@@ -3,3 +3,6 @@ extern void save_atags(struct tag *tags);
 #else
 static inline void save_atags(struct tag *tags) { }
 #endif
+
+void convert_to_tag_list(struct tag *tags);
+struct machine_desc *setup_machine_tags(phys_addr_t __atags_pointer, unsigned int machine_nr);

arch/arm/kernel/atags_compat.c renamed from arch/arm/kernel/compat.c +2 -2

similarity index 99%
rename from arch/arm/kernel/compat.c
rename to arch/arm/kernel/atags_compat.c
index 925652318b..5236ad38f4 100644
@@ -1,5 +1,5 @@
 /*
- *  linux/arch/arm/kernel/compat.c
+ *  linux/arch/arm/kernel/atags_compat.c
  *
  *  Copyright (C) 2001 Russell King
  *

@@ -26,7 +26,7 @@
 
 #include <asm/mach/arch.h>
 
-#include "compat.h"
+#include "atags.h"
 
 /*
  * Usage:

arch/arm/kernel/atags_parse.c new file +238 -0

238 lines not on this page · raw message

arch/arm/kernel/atags_proc.c renamed from arch/arm/kernel/atags.c +0 -0

similarity index 100%
rename from arch/arm/kernel/atags.c
rename to arch/arm/kernel/atags_proc.c

arch/arm/kernel/compat.h deleted +0 ~~-11~~

deleted file mode 100644
index 39264ab1b9..0000000000
@@ -1,11 +0,0 @@
-/*
- *  linux/arch/arm/kernel/compat.h
- *
- *  Copyright (C) 2001 Russell King
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
-*/
-
-extern void convert_to_tag_list(struct tag *tags);

arch/arm/kernel/setup.c +1 ~~-235~~

292 lines not on this page · raw message

Signature · 1 line

1.7.12.84.gefa6462

Nicolas Pitre

author

2012-08-30 21:10 UTC #1 lore raw

PATCH 2/2 ARM: allow for ATAGS to be configured out when DT support is selected

Now that ATAGS support is well contained, we can easily remove it from the kernel build if so desired. It has to explicitly be disabled, and only when DT support is selected.

Note: disabling kernel ATAGS support does not prevent the usage of CONFIG_ARM_ATAG_DTB_COMPAT.

Signed-off-by Nicolas Pitre <[email protected]>

---
 arch/arm/Kconfig         | 26 +++++++++++++++++++-------
 arch/arm/kernel/Makefile |  5 +++--
 arch/arm/kernel/atags.h  | 11 +++++++++++
 3 files changed, 33 insertions(+), 9 deletions(-)

arch/arm/Kconfig +19 -7

index c5f9ae5dbd..5c7302e208 100644
@@ -1891,12 +1891,6 @@ config CC_STACKPROTECTOR
 	  neutralized via a kernel panic.
 	  This feature requires gcc version 4.2 or above.
 
-config DEPRECATED_PARAM_STRUCT
-	bool "Provide old way to pass kernel parameters"
-	help
-	  This was deprecated in 2001 and announced to live on for 5 years.
-	  Some old boot loaders still use this way.
-
 endmenu
 
 menu "Boot options"

@@ -1909,6 +1903,23 @@ config USE_OF
 	help
 	  Include support for flattened device tree machine descriptions.
 
+config ATAGS
+	bool "Support for the traditional ATAGS boot data passing" if USE_OF
+	default y
+	help
+	  This is the traditional way of passing data to the kernel at boot
+	  time. If you are solely relying on the flattened device tree (or
+	  the ARM_ATAG_DTB_COMPAT option) then you may unselect this option
+	  to remove ATAGS support from your kernel binary.  If unsure,
+	  leave this to y.
+
+config DEPRECATED_PARAM_STRUCT
+	bool "Provide old way to pass kernel parameters"
+	depends on ATAGS
+	help
+	  This was deprecated in 2001 and announced to live on for 5 years.
+	  Some old boot loaders still use this way.
+
 # Compressed boot loader in ROM.  Yes, we really want to ask about
 # TEXT and BSS so we preserve their values in the config files.
 config ZBOOT_ROM_TEXT

@@ -2035,6 +2046,7 @@ config CMDLINE
 choice
 	prompt "Kernel command line type" if CMDLINE != ""
 	default CMDLINE_FROM_BOOTLOADER
+	depends on ATAGS
 
 config CMDLINE_FROM_BOOTLOADER
 	bool "Use bootloader kernel arguments if available"

@@ -2104,7 +2116,7 @@ config KEXEC
 
 config ATAGS_PROC
 	bool "Export atags in procfs"
-	depends on KEXEC
+	depends on ATAGS && KEXEC
 	default y
 	help
 	  Should the atags used to boot the kernel be exported in an "atags"

arch/arm/kernel/Makefile +3 -2

index 086c9d3bc3..79e346a5d7 100644
@@ -15,10 +15,12 @@ CFLAGS_REMOVE_return_address.o = -pg
 
 # Object file lists.
 
-obj-y		:= atags_parse.o elf.o entry-armv.o entry-common.o irq.o opcodes.o \
+obj-y		:= elf.o entry-armv.o entry-common.o irq.o opcodes.o \
 		   process.o ptrace.o return_address.o sched_clock.o \
 		   setup.o signal.o stacktrace.o sys_arm.o time.o traps.o
 
+obj-$(CONFIG_ATAGS)		+= atags_parse.o
+obj-$(CONFIG_ATAGS_PROC)	+= atags_proc.o
 obj-$(CONFIG_DEPRECATED_PARAM_STRUCT) += atags_compat.o
 
 obj-$(CONFIG_LEDS)		+= leds.o

@@ -52,7 +54,6 @@ test-kprobes-objs		+= kprobes-test-thumb.o
 else
 test-kprobes-objs		+= kprobes-test-arm.o
 endif
-obj-$(CONFIG_ATAGS_PROC)	+= atags_proc.o
 obj-$(CONFIG_OABI_COMPAT)	+= sys_oabi-compat.o
 obj-$(CONFIG_ARM_THUMBEE)	+= thumbee.o
 obj-$(CONFIG_KGDB)		+= kgdb.o

arch/arm/kernel/atags.h +11 -0

index a888fdd381..9edc969233 100644
@@ -5,4 +5,15 @@ static inline void save_atags(struct tag *tags) { }
 #endif
 
 void convert_to_tag_list(struct tag *tags);
+
+#ifdef CONFIG_ATAGS
 struct machine_desc *setup_machine_tags(phys_addr_t __atags_pointer, unsigned int machine_nr);
+#else
+static inline struct machine_desc *
+setup_machine_tags(phys_addr_t __atags_pointer, unsigned int machine_nr)
+{
+	early_print("no ATAGS support: can't continue\n");
+	while (true);
+	unreachable();
+}
+#endif

Signature · 1 line

1.7.12.84.gefa6462

Linus Walleij

2012-09-01 00:23 UTC #2 lore raw

PATCH 2/2 ARM: allow for ATAGS to be configured out when DT support is selected

Quoted 3 lines · Nicolas Pitre

Now that ATAGS support is well contained, we can easily remove it from the kernel build if so desired. It has to explicitly be disabled, and only when DT support is selected.

I patched this on top of my Integrator patch stack and disabled the ATAGS, it just works.

Tested-by Linus Walleij <[email protected]>

I'd suggest you to put this into Russells tracker then?

Yours,
Linus Walleij

Nicolas Pitre

author

2012-09-01 01:48 UTC #3 lore raw

PATCH 2/2 ARM: allow for ATAGS to be configured out when DT support is selected

Quoted 11 lines · Linus Walleij

Quoted 3 lines · Nicolas Pitre
Now that ATAGS support is well contained, we can easily remove it from the kernel build if so desired. It has to explicitly be disabled, and only when DT support is selected.
I patched this on top of my Integrator patch stack and disabled the ATAGS, it just works.
Tested-by Linus Walleij <[email protected]>

Thanks.

Quoted 1 line

I'd suggest you to put this into Russells tracker then?

Certainly. I just wanted someone else than myself to test it / look at it before I do so.

Nicolas

Arnd Bergmann

2012-09-01 20:25 UTC #4 lore raw

PATCH 2/2 ARM: allow for ATAGS to be configured out when DT support is selected

In reply to Nicolas Pitre

Quoted 9 lines · Nicolas Pitre

Now that ATAGS support is well contained, we can easily remove it from the kernel build if so desired. It has to explicitly be disabled, and only when DT support is selected.
Note: disabling kernel ATAGS support does not prevent the usage of CONFIG_ARM_ATAG_DTB_COMPAT.
...

arch/arm/Kconfig config USE_OF · line 1914

Quoted 9 lines

arch/arm/Kconfig +9 -0

+config ATAGS
+	bool "Support for the traditional ATAGS boot data passing" if USE_OF
+	default y
+	help
+	  This is the traditional way of passing data to the kernel at boot
+	  time. If you are solely relying on the flattened device tree (or
+	  the ARM_ATAG_DTB_COMPAT option) then you may unselect this option
+	  to remove ATAGS support from your kernel binary.  If unsure,
+	  leave this to y.

That's a clever way of implementing it, I had not though of making it an optional default-y symbol.

Acked-by Arnd Bergmann <[email protected]>

Should we do patches to the individual platforms bsaed on this to disable the ATAG based board files when CONFIG_ATAG is disabled?

Arnd

Nicolas Pitre

author

2012-09-04 02:56 UTC #5 lore raw

PATCH 2/2 ARM: allow for ATAGS to be configured out when DT support is selected

Quoted 23 lines · Arnd Bergmann

Quoted 9 lines · Nicolas Pitre
Now that ATAGS support is well contained, we can easily remove it from the kernel build if so desired. It has to explicitly be disabled, and only when DT support is selected.
Note: disabling kernel ATAGS support does not prevent the usage of CONFIG_ARM_ATAG_DTB_COMPAT.
...
arch/arm/Kconfig config USE_OF · line 1914
Quoted 9 lines
arch/arm/Kconfig +9 -0
+config ATAGS
+	bool "Support for the traditional ATAGS boot data passing" if USE_OF
+	default y
+	help
+	  This is the traditional way of passing data to the kernel at boot
+	  time. If you are solely relying on the flattened device tree (or
+	  the ARM_ATAG_DTB_COMPAT option) then you may unselect this option
+	  to remove ATAGS support from your kernel binary.  If unsure,
+	  leave this to y.
That's a clever way of implementing it, I had not though of making it an optional default-y symbol.

Quoted 1 line

Acked-by Arnd Bergmann <[email protected]>

Thanks.

Quoted 2 lines

Should we do patches to the individual platforms bsaed on this to disable the ATAG based board files when CONFIG_ATAG is disabled?

Well... that could be a good thing to make them depend on ATAGS indeed. But that can be done incrementally in later patches.

Nicolas

Will Deacon

2012-09-02 15:54 UTC #6 lore raw

PATCH 2/2 ARM: allow for ATAGS to be configured out when DT support is selected

In reply to Nicolas Pitre

Quoted 19 lines · Nicolas Pitre

Now that ATAGS support is well contained, we can easily remove it from the kernel build if so desired. It has to explicitly be disabled, and only when DT support is selected.
Note: disabling kernel ATAGS support does not prevent the usage of CONFIG_ARM_ATAG_DTB_COMPAT.
Signed-off-by Nicolas Pitre <[email protected]>
---
 arch/arm/Kconfig         | 26 +++++++++++++++++++-------
 arch/arm/kernel/Makefile |  5 +++--
 arch/arm/kernel/atags.h  | 11 +++++++++++
 3 files changed, 33 insertions(+), 9 deletions(-)
arch/arm/Kconfig +0 -0
index c5f9ae5dbd..5c7302e208 100644

arch/arm/Kconfig config CC_STACKPROTECTOR · line 1894

Quoted 10 lines

arch/arm/Kconfig +0 -6

@@ -1891,12 +1891,6 @@ config CC_STACKPROTECTOR
 	  neutralized via a kernel panic.
 	  This feature requires gcc version 4.2 or above.
 
-config DEPRECATED_PARAM_STRUCT
-	bool "Provide old way to pass kernel parameters"
-	help
-	  This was deprecated in 2001 and announced to live on for 5 years.
-	  Some old boot loaders still use this way.
-
 endmenu

Since you're in this area, do we need to carry this forward? If somebody is using it then obviously we have to keep it but it might be worth asking around.

Back on topic, this looks good to me:

Acked-by Will Deacon <[email protected]>

Will

Nicolas Pitre

author

2012-09-04 02:47 UTC #7 lore raw

PATCH 2/2 ARM: allow for ATAGS to be configured out when DT support is selected

Quoted 23 lines · Will Deacon

Quoted 22 lines · Nicolas Pitre
Now that ATAGS support is well contained, we can easily remove it from the kernel build if so desired. It has to explicitly be disabled, and only when DT support is selected.
Note: disabling kernel ATAGS support does not prevent the usage of CONFIG_ARM_ATAG_DTB_COMPAT.
Signed-off-by Nicolas Pitre <[email protected]>
---
 arch/arm/Kconfig         | 26 +++++++++++++++++++-------
 arch/arm/kernel/Makefile |  5 +++--
 arch/arm/kernel/atags.h  | 11 +++++++++++
 3 files changed, 33 insertions(+), 9 deletions(-)
arch/arm/Kconfig +0 -0
index c5f9ae5dbd..5c7302e208 100644
@@ -1891,12 +1891,6 @@ config CC_STACKPROTECTOR
 	  neutralized via a kernel panic.
 	  This feature requires gcc version 4.2 or above.
 

Quoted 11 lines

arch/arm/Kconfig config CC_STACKPROTECTOR · line 1894
Quoted 7 lines
arch/arm/Kconfig +0 -6
-config DEPRECATED_PARAM_STRUCT
-	bool "Provide old way to pass kernel parameters"
-	help
-	  This was deprecated in 2001 and announced to live on for 5 years.
-	  Some old boot loaders still use this way.
-
 endmenu
Since you're in this area, do we need to carry this forward? If somebody is using it then obviously we have to keep it but it might be worth asking around.

That should be a separate patch if that has to be dropped. Right now that code is already in a file of its own and not getting in the way of anything else, and I didn't want to change any behavior on legacy platforms.

Quoted 3 lines

Back on topic, this looks good to me:
Acked-by Will Deacon <[email protected]>

Thanks.

Nicolas

Olof Johansson

2012-09-05 05:24 UTC #8 lore raw

PATCH 2/2 ARM: allow for ATAGS to be configured out when DT support is selected

In reply to Nicolas Pitre

Quoted 8 lines · Nicolas Pitre

Now that ATAGS support is well contained, we can easily remove it from the kernel build if so desired. It has to explicitly be disabled, and only when DT support is selected.
Note: disabling kernel ATAGS support does not prevent the usage of CONFIG_ARM_ATAG_DTB_COMPAT.
Signed-off-by Nicolas Pitre <[email protected]>

Nice!

Acked-by Olof Johansson <[email protected]>

-Olof