diff options
| -rw-r--r-- | arch/i386/cpu/start.S | 36 | ||||
| -rw-r--r-- | arch/i386/cpu/start16.S | 8 | ||||
| -rw-r--r-- | board/eNET/config.mk | 2 | ||||
| -rw-r--r-- | board/eNET/u-boot.lds | 9 |
4 files changed, 43 insertions, 12 deletions
diff --git a/arch/i386/cpu/start.S b/arch/i386/cpu/start.S index 1980f1a..3cea04b 100644 --- a/arch/i386/cpu/start.S +++ b/arch/i386/cpu/start.S @@ -33,7 +33,27 @@ .type _start, @function .globl _i386boot_start _i386boot_start: + /* + * This is the fail safe 32-bit bootstrap entry point. The + * following code is not executed from a cold-reset (actually, a + * lot of it is, but from real-mode after cold reset. It is + * repeated here to put the board into a state as close to cold + * reset as necessary) + */ + cli + cld + + /* Turn of cache (this might require a 486-class CPU) */ + movl %cr0, %eax + orl $0x60000000,%eax + movl %eax, %cr0 + wbinvd + + /* Tell 32-bit code it is being entered from an in-RAM copy */ + movw $0x0000, %bx _start: + /* This is the 32-bit cold-reset entry point */ + movl $0x18,%eax /* Load our segement registes, the * gdt have already been loaded by start16.S */ movw %ax,%fs @@ -42,6 +62,18 @@ _start: movw %ax,%es movw %ax,%ss + /* Clear the interupt vectors */ + lidt blank_idt_ptr + + /* + * Skip low-level board and memory initialization if not starting + * from cold-reset. This allows us to do a fail safe boot-strap + * into a new build of U-Boot from a known-good boot flash + */ + movw $0x0001, %ax + cmpw %ax, %bx + jne mem_init_ret + /* We call a few functions in the board support package * since we have no stack yet we'll have to use %ebp * to store the return address */ @@ -138,3 +170,7 @@ stack_ok: die: hlt jmp die hlt + +blank_idt_ptr: + .word 0 /* limit */ + .long 0 /* base */ diff --git a/arch/i386/cpu/start16.S b/arch/i386/cpu/start16.S index 1ebb6bc..5e33aa1 100644 --- a/arch/i386/cpu/start16.S +++ b/arch/i386/cpu/start16.S @@ -45,10 +45,8 @@ board_init16_ret: wbinvd /* load the descriptor tables */ -o32 cs lidt idt_ptr o32 cs lgdt gdt_ptr - /* Now, we enter protected mode */ movl %cr0, %eax orl $1,%eax @@ -57,6 +55,8 @@ o32 cs lgdt gdt_ptr /* Flush the prefetch queue */ jmp ff ff: + /* Tell 32-bit code it is being entered from hard-reset */ + movw $0x0001, %bx /* Finally jump to the 32bit initialization code */ movw $code32start, %ax @@ -68,10 +68,6 @@ code32start: .long _start /* offset */ .word 0x10 /* segment */ -idt_ptr: - .word 0 /* limit */ - .long 0 /* base */ - gdt_ptr: .word 0x30 /* limit (48 bytes = 6 GDT entries) */ .long BOOT_SEG + gdt /* base */ diff --git a/board/eNET/config.mk b/board/eNET/config.mk index dcde7fc..63a58fd 100644 --- a/board/eNET/config.mk +++ b/board/eNET/config.mk @@ -21,7 +21,7 @@ # MA 02111-1307 USA # -TEXT_BASE = 0x38040000 +TEXT_BASE = 0x06000000 CFLAGS_common/dlmalloc.o += -Wa,--no-warn -fno-strict-aliasing PLATFORM_RELFLAGS += -fvisibility=hidden PLATFORM_CPPFLAGS += -fno-dwarf2-cfi-asm diff --git a/board/eNET/u-boot.lds b/board/eNET/u-boot.lds index 0d74021..7b0ffaa 100644 --- a/board/eNET/u-boot.lds +++ b/board/eNET/u-boot.lds @@ -27,7 +27,7 @@ ENTRY(_start) SECTIONS { - . = 0x38040000; /* Location of bootcode in flash */ + . = 0x06000000; /* Location of bootcode in flash */ _i386boot_text_start = .; .text : { *(.text); } @@ -97,14 +97,13 @@ SECTIONS * at reset and the code have to fit. * The fff0 offset of resetvec is important, however. */ - . = 0xfffffe00; - .start32 : AT (0x3807fe00) { *(.start32); } + .start32 : AT (0x0603fe00) { *(.start32); } . = 0xf800; - .start16 : AT (0x3807f800) { *(.start16); } + .start16 : AT (0x0603f800) { *(.start16); } . = 0xfff0; - .resetvec : AT (0x3807fff0) { *(.resetvec); } + .resetvec : AT (0x0603fff0) { *(.resetvec); } _i386boot_end = (LOADADDR(.resetvec) + SIZEOF(.resetvec) ); } |