CAR_GLOBAL: Define section details once

Improve clang compatibility by dropping an opaque hack

The section attribute was only ever meant for specifying
section names, not their properties - otherwise they would
have provided section(name,attribute,class) instead of only
section(name).

The hack to add attribute and class to the name, and commenting
out the "real" definitions inserted by the compiler (see the
terminating "#"), is refused by clang developers.

This is a cleaner implementation in that the section is first
declared with its properties, then used later-on, expecting that
later conflicting declarations are ignored.

It can still break in two ways:
1. The assembler or linker could complain about a section declared
in two different ways.
2. The assembler could just use the latest declaration, not the first,
to determine the section's properties.

I won't sort these out unless they actually happen.


Change-Id: I4640b0fc397b301102dde6dc3ea1a078ce9edf1c
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-on: http://review.coreboot.org/4716
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Aaron Durbin <adurbin@google.com>

src/arch/x86/include/arch/early_variables.h

@@ -21,8 +21,12 @@
 #define ARCH_EARLY_VARIABLES_H
 
 #ifdef __PRE_RAM__
-#define CAR_GLOBAL __attribute__((section(".car.global_data,\"w\",@nobits#")))
-#define CAR_CBMEM __attribute__((section(".car.cbmem_console,\"w\",@nobits#")))
+asm(".section .car.global_data,\"w\",@nobits");
+asm(".previous");
+asm(".section .car.cbmem_console,\"w\",@nobits");
+asm(".previous");
+#define CAR_GLOBAL __attribute__((section(".car.global_data")))
+#define CAR_CBMEM __attribute__((section(".car.cbmem_console")))
 #else
 #define CAR_GLOBAL
 #define CAR_CBMEM