ARM: 7506/1: 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 <nico@linaro.org>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index c5f9ae5dbd1ad04da804d68e475d3b4b230832f6..5c7302e208ce8cc2c2f34999666e358db456e2ef 100644 (file)
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -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"

diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 086c9d3bc360a00b8abf903481b2ee1a10e5743b..79e346a5d78bd59ccfdf571575a8b5dfd2d28251 100644 (file)
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -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

diff --git a/arch/arm/kernel/atags.h b/arch/arm/kernel/atags.h
index a888fdd381b5ca192946e10e4b95f3a80b0b1644..9edc9692332d1a368a293f38e0a9543c2102a751 100644 (file)
--- a/arch/arm/kernel/atags.h
+++ b/arch/arm/kernel/atags.h
@@ -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