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common: Rewrite hiding the end of memory

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As the name may be confusing, the CONFIG_SYS_MEM_TOP_HIDE reserves
some memory from the end of ram, tracked by gd->ram_size. It is not
always the top of u-boot visible memory. Rewrite the macro with a
weak function to provide flexibility for complex calcuation. Legacy
use of this macro is still supported.

Signed-off-by: York Sun <yorksun@freescale.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
York Sun 2015-12-07 11:05:29 -08:00
parent c107c0c05c
commit aabd7ddb88
2 changed files with 16 additions and 9 deletions
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2
README
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@ -3877,7 +3877,7 @@ Configuration Settings:
the RAM base is not zero, or RAM is divided into banks,
this variable needs to be recalcuated to get the address.
- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
- CONFIG_SYS_MEM_TOP_HIDE:
If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
this specified memory area will get subtracted from the top
(end) of RAM and won't get "touched" at all by U-Boot. By

23
common/board_f.c
View file

@ -317,6 +317,15 @@ __weak ulong board_get_usable_ram_top(ulong total_size)
return gd->ram_top;
}
__weak phys_size_t board_reserve_ram_top(phys_size_t ram_size)
{
#ifdef CONFIG_SYS_MEM_TOP_HIDE
return ram_size - CONFIG_SYS_MEM_TOP_HIDE;
#else
return ram_size;
#endif
}
static int setup_dest_addr(void)
{
debug("Monitor len: %08lX\n", gd->mon_len);
@ -333,19 +342,17 @@ static int setup_dest_addr(void)
*/
gd->secure_ram = gd->ram_size;
#endif
#if defined(CONFIG_SYS_MEM_TOP_HIDE)
/*
* Subtract specified amount of memory to hide so that it won't
* get "touched" at all by U-Boot. By fixing up gd->ram_size
* the Linux kernel should now get passed the now "corrected"
* memory size and won't touch it either. This should work
* for arch/ppc and arch/powerpc. Only Linux board ports in
* arch/powerpc with bootwrapper support, that recalculate the
* memory size from the SDRAM controller setup will have to
* get fixed.
* memory size and won't touch it either. This has been used
* by arch/powerpc exclusively. Now ARMv8 takes advantage of
* thie mechanism. If memory is split into banks, addresses
* need to be calculated.
*/
gd->ram_size -= CONFIG_SYS_MEM_TOP_HIDE;
#endif
gd->ram_size = board_reserve_ram_top(gd->ram_size);
#ifdef CONFIG_SYS_SDRAM_BASE
gd->ram_top = CONFIG_SYS_SDRAM_BASE;
#endif