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x86: make LOAD_FROM_32_BIT visible for platforms

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This option is useful not only for development, but for the platforms
where U-Boot is run from custom ROM bootloader. For example, Intel
Edison is that board.

Make this option visible that platforms can select it if needed.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
This commit is contained in:
Andy Shevchenko 2017-02-05 16:52:00 +03:00 committed by Bin Meng
parent bda40d5634
commit 446d4e048e
2 changed files with 10 additions and 10 deletions
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8
arch/x86/Kconfig
View File

@ -195,6 +195,14 @@ config SYS_X86_START16
depends on X86_RESET_VECTOR
default 0xfffff800
config X86_LOAD_FROM_32_BIT
bool "Boot from a 32-bit program"
help
Define this to boot U-Boot from a 32-bit program which sets
the GDT differently. This can be used to boot directly from
any stage of coreboot, for example, bypassing the normal
payload-loading feature.
config BOARD_ROMSIZE_KB_512
bool
config BOARD_ROMSIZE_KB_1024

12
arch/x86/cpu/start.S
View File

@ -18,14 +18,6 @@
#include <generated/generic-asm-offsets.h>
#include <generated/asm-offsets.h>
/*
* Define this to boot U-Boot from a 32-bit program which sets the GDT
* differently. This can be used to boot directly from any stage of coreboot,
* for example, bypassing the normal payload-loading feature.
* This is only useful for development.
*/
#undef LOAD_FROM_32_BIT
.section .text
.code32
.globl _start
@ -76,7 +68,7 @@ _start:
/* Save table pointer */
movl %ecx, %esi
#ifdef LOAD_FROM_32_BIT
#ifdef CONFIG_X86_LOAD_FROM_32_BIT
lgdt gdt_ptr2
#endif
@ -233,7 +225,7 @@ multiboot_header:
/* entry addr */
.long CONFIG_SYS_TEXT_BASE
#ifdef LOAD_FROM_32_BIT
#ifdef CONFIG_X86_LOAD_FROM_32_BIT
/*
* The following Global Descriptor Table is just enough to get us into
* 'Flat Protected Mode' - It will be discarded as soon as the final