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common/board_f: remove XTRN_DECLARE_GLOBAL_DATA_PTR dead code

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The XTRN_DECLARE_GLOBAL_DATA_PTR declarations in ppc code are permanently
commented out, so there are no users for this macro:
 #if 1
   #define DECLARE_GLOBAL_DATA_PTR   register volatile gd_t *gd asm ("r2")
 #else /* We could use plain global data, but the resulting code is bigger */
   #define XTRN_DECLARE_GLOBAL_DATA_PTR   extern
   #define DECLARE_GLOBAL_DATA_PTR     XTRN_DECLARE_GLOBAL_DATA_PTR \
                                       gd_t *gd
 #endif

Remove all references to this macro, but add a documentation note regarding
the possibility of using plain global data for the GD pointer.

Signed-off-by: Ovidiu Panait <ovpanait@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
This commit is contained in:
Ovidiu Panait 2022-09-13 21:31:26 +03:00 committed by Tom Rini
parent a70c75caba
commit 181cbd4017
3 changed files with 5 additions and 17 deletions
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6
arch/powerpc/include/asm/global_data.h
View File

@ -92,12 +92,6 @@ struct arch_global_data {
#include <asm-generic/global_data.h>
#if 1
#define DECLARE_GLOBAL_DATA_PTR register volatile gd_t *gd asm ("r2")
#else /* We could use plain global data, but the resulting code is bigger */
#define XTRN_DECLARE_GLOBAL_DATA_PTR extern
#define DECLARE_GLOBAL_DATA_PTR XTRN_DECLARE_GLOBAL_DATA_PTR \
gd_t *gd
#endif
#endif /* __ASM_GBL_DATA_H */

11
common/board_f.c
View File

@ -59,18 +59,7 @@
#include <linux/errno.h>
#include <linux/log2.h>
/*
* Pointer to initial global data area
*
* Here we initialize it if needed.
*/
#ifdef XTRN_DECLARE_GLOBAL_DATA_PTR
#undef XTRN_DECLARE_GLOBAL_DATA_PTR
#define XTRN_DECLARE_GLOBAL_DATA_PTR /* empty = allocate here */
DECLARE_GLOBAL_DATA_PTR = (gd_t *)(CONFIG_SYS_INIT_GD_ADDR);
#else
DECLARE_GLOBAL_DATA_PTR;
#endif
/*
* TODO(sjg@chromium.org): IMO this code should be

5
doc/develop/global_data.rst
View File

@ -36,6 +36,11 @@ On most architectures the global data pointer is stored in a register.
The sandbox, x86_64, and Xtensa are notable exceptions.
Current implementation uses a register for the GD pointer because this results
in smaller code. However, using plain global data for the GD pointer would be
possible too (and simpler, as it does not require the reservation of a specific
register for it), but the resulting code is bigger.
Clang for ARM does not support assigning a global register. When using Clang
gd is defined as an inline function using assembly code. This adds a few bytes
to the code size.