arm: Remove CAR_MIGRATE Kconfig and associated cruft

This is essentially a revert of commit 5a1469d5. The CAR_MIGRATE
mechanism is only useful to migrate variables from a special region
(e.g. cache as RAM) into DRAM-backed CBMEM between different parts of
the romstage (it does not persist into ramstage). Since ARM devices use
SRAM for which there is no reason to become inaccessible in later parts
of the romstage, this mechanism isn't useful for them. Removing it makes
the romstage.ld script much simpler, which has the nice side-effect of
putting the BSS at the end of the memory image (so that cbfstool can
actually figure out that it doesn't need to be part of the ROM image).

BUG=None
TEST=Still boots and the romstage BSS is no longer part of the load
size in the CBFS image.

Change-Id: I50e91d8bd51b5deb19446d9da48699edecbef6ea
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/176761
Reviewed-by: David Hendricks <dhendrix@chromium.org>

src/arch/arm/include/arch/early_variables.h

@@ -20,40 +20,17 @@
 #ifndef ARCH_EARLY_VARIABLES_H
 #define ARCH_EARLY_VARIABLES_H
 
-#ifdef __PRE_RAM__
-#define CAR_GLOBAL __attribute__((section(".car.global_data")))
-#define CAR_CBMEM __attribute__((section(".car.cbmem_console")))
-#else
-#define CAR_GLOBAL
-#define CAR_CBMEM
+#if CONFIG_CAR_MIGRATION
+	#error "This is ARM, silly... we don't have CAR here."
 #endif
 
-#if CONFIG_CAR_MIGRATION && defined(__PRE_RAM__)
-#define CAR_MIGRATE_ATTR __attribute__ ((used,section (".car.migrate")))
+#define CAR_GLOBAL
+#define CAR_CBMEM
 
-/* Call migrate_fn_() when CAR globals are migrated. */
-#define CAR_MIGRATE(migrate_fn_) \
-	static void (* const migrate_fn_ ## _ptr)(void) CAR_MIGRATE_ATTR = \
-	migrate_fn_;
-
-/* Get the correct pointer for the CAR global variable. */
-void *car_get_var_ptr(void *var);
-
-/* Get and set a primitive type global variable. */
-#define car_get_var(var) \
-	*(typeof(var) *)car_get_var_ptr(&(var))
-#define car_set_var(var, val) \
-	do { car_get_var(var) = (val); } while(0)
-
-/* Migrate the CAR variables to memory. */
-void car_migrate_variables(void);
-
-#else
 #define CAR_MIGRATE(migrate_fn_)
 static inline void *car_get_var_ptr(void *var) { return var; }
 #define car_get_var(var) (var)
 #define car_set_var(var, val) do { (var) = (val); } while (0)
 static inline void car_migrate_variables(void) { }
-#endif
 
 #endif

src/arch/arm/romstage.ld

@@ -33,7 +33,6 @@ ENTRY(stage_entry)
 
 SECTIONS
 {
-	/* TODO make this a configurable option (per chipset). */
 	. = CONFIG_ROMSTAGE_BASE;
 
 	.romtext . : {
@@ -48,11 +47,7 @@ SECTIONS
 		*(.rodata);
 		*(.machine_param);
 		*(.data);
-		. = ALIGN(16);
-		_car_migrate_start = .;
-		*(.car.migrate);
-		_car_migrate_end = .;
-		. = ALIGN(16);
+		. = ALIGN(8);
 		_erom = .;
 	}
 
@@ -70,32 +65,8 @@ SECTIONS
 
 	_ebss = .;
 
-	.car.data . : {
-		. = ALIGN(8);
-		_car_data_start = .;
-		*(.car.global_data);
-		. = ALIGN(8);
-		/* The cbmem_console section comes last to take advantage of
-		 * a zero-sized array to hold the memconsole contents that
-		 * grows to a bound of CONFIG_CONSOLE_CAR_BUFFER_SIZE. However,
-		 * collisions within the cache-as-ram region cannot be
-		 * statically checked because the cache-as-ram region usage is
-		 * cpu/chipset dependent. */
-		*(.car.cbmem_console);
-		_car_data_end = .;
-	}
-
 	_end = .;
 
-	/* TODO: check if we are running out of SRAM. Below check is not good
-	 * enough though because SRAM has different size on different CPUs
-	 * and not all SRAM is available to the romstage. On Exynos, some is
-	 * used for BL1, the bootblock and the stack.
-	 *
-	 * _bogus = ASSERT((_end - _start + EXPECTED_CBMEM_CONSOLE_SIZE <= \
-	 * 				0x54000), "SRAM area is too full");
-	 */
-
 	/* Discard the sections we don't need/want */
 	/DISCARD/ : {
 		*(.comment)

src/soc/samsung/exynos5250/Kconfig

@@ -5,7 +5,6 @@ config CPU_SAMSUNG_EXYNOS5250
 	select HAVE_UART_SPECIAL
 	select EARLY_CONSOLE
 	select DYNAMIC_CBMEM
-	select CAR_MIGRATION
 	select ARM_BOOTBLOCK_ARMV7
 	select ARM_ROMSTAGE_ARMV7
 	select ARM_RAMSTAGE_ARMV7

src/soc/samsung/exynos5420/Kconfig

@@ -6,7 +6,6 @@ config CPU_SAMSUNG_EXYNOS5420
 	select EARLY_CONSOLE
 	select RELOCATABLE_MODULES
 	select DYNAMIC_CBMEM
-	select CAR_MIGRATION
 	select ARM_BOOTBLOCK_ARMV7
 	select ARM_ROMSTAGE_ARMV7
 	select ARM_RAMSTAGE_ARMV7