X-Git-Url: https://git.sur5r.net/?a=blobdiff_plain;f=arch%2Fx86%2Fcpu%2Fstart.S;h=a5cba1cf2a766680e3e1b8ab6290bee2aa8a0191;hb=806f86bd826e7a0fbefd4f34c550df400905992a;hp=2e5f9da75673c55397d58ec18d858f5fa1c34a4a;hpb=9da7e3daf31d7c0c8478a57544bfdd6245e53ff3;p=u-boot diff --git a/arch/x86/cpu/start.S b/arch/x86/cpu/start.S index 2e5f9da756..a5cba1cf2a 100644 --- a/arch/x86/cpu/start.S +++ b/arch/x86/cpu/start.S @@ -18,6 +18,14 @@ #include #include +/* + * 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 @@ -25,11 +33,11 @@ .globl _x86boot_start _x86boot_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) + * This is the fail-safe 32-bit bootstrap entry point. + * + * This code is used when booting from another boot loader like + * coreboot or EFI. So we repeat some of the same init found in + * start16. */ cli cld @@ -41,19 +49,38 @@ _x86boot_start: wbinvd /* Tell 32-bit code it is being entered from an in-RAM copy */ - movw $GD_FLG_WARM_BOOT, %bx + movl $GD_FLG_WARM_BOOT, %ebx + + /* + * Zero the BIST (Built-In Self Test) value since we don't have it. + * It must be 0 or the previous loader would have reported an error. + */ + movl $0, %ebp + jmp 1f + + /* Add a way for tools to discover the _start entry point */ + .align 4 + .long 0x12345678 _start: /* - * This is the 32-bit cold-reset entry point. Initialize %bx to 0 - * in case we're preceeded by some sort of boot stub. + * This is the 32-bit cold-reset entry point, coming from start16. + * Set %ebx to GD_FLG_COLD_BOOT to indicate this. */ - movw $GD_FLG_COLD_BOOT, %bx -1: + movl $GD_FLG_COLD_BOOT, %ebx + /* Save BIST */ movl %eax, %ebp +1: + + /* Save table pointer */ + movl %ecx, %esi - /* Load the segement registes to match the gdt loaded in start16.S */ +#ifdef LOAD_FROM_32_BIT + lgdt gdt_ptr2 +#endif + + /* Load the segement registers to match the GDT loaded in start16.S */ movl $(X86_GDT_ENTRY_32BIT_DS * X86_GDT_ENTRY_SIZE), %eax movw %ax, %fs movw %ax, %ds @@ -64,7 +91,11 @@ _start: /* Clear the interrupt vectors */ lidt blank_idt_ptr - /* Early platform init (setup gpio, etc ) */ + /* + * Critical early platform init - generally not used, we prefer init + * to happen later when we have a console, in case something goes + * wrong. + */ jmp early_board_init .globl early_board_init_ret early_board_init_ret: @@ -79,14 +110,13 @@ car_init_ret: * We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM, * or fully initialised SDRAM - we really don't care which) * starting at CONFIG_SYS_CAR_ADDR to be used as a temporary stack - * and early malloc area. The MRC requires some space at the top. + * and early malloc() area. The MRC requires some space at the top. * * Stack grows down from top of CAR. We have: * * top-> CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE * MRC area - * global_data - * x86 global descriptor table + * global_data with x86 global descriptor table * early malloc area * stack * bottom-> CONFIG_SYS_CAR_ADDR @@ -97,63 +127,51 @@ car_init_ret: #endif #else /* - * When we get here after car_init, esp points to a temporary stack - * and esi holds the HOB list address returned by the FSP. + * U-Boot enters here twice. For the first time it comes from + * car_init_done() with esp points to a temporary stack and esi + * set to zero. For the second time it comes from fsp_init_done() + * with esi holding the HOB list address returned by the FSP. */ #endif - - /* Reserve space on stack for global data */ - subl $GENERATED_GBL_DATA_SIZE, %esp - - /* Align global data to 16-byte boundary */ - andl $0xfffffff0, %esp - post_code(POST_START_STACK) - - /* Zero the global data since it won't happen later */ - xorl %eax, %eax - movl $GENERATED_GBL_DATA_SIZE, %ecx - movl %esp, %edi - rep stosb - -#ifdef CONFIG_HAVE_FSP - /* Store HOB list */ - movl %esp, %edx - addl $GD_HOB_LIST, %edx - movl %esi, (%edx) + /* Set up global data */ + mov %esp, %eax + call board_init_f_alloc_reserve + mov %eax, %esp + call board_init_f_init_reserve + +#ifdef CONFIG_DEBUG_UART + call debug_uart_init #endif - /* Setup first parameter to setup_gdt, pointer to global_data */ - movl %esp, %eax - - /* Reserve space for global descriptor table */ - subl $X86_GDT_SIZE, %esp - - /* Align temporary global descriptor table to 16-byte boundary */ - andl $0xfffffff0, %esp - movl %esp, %ecx + /* Get address of global_data */ + mov %fs:0, %edx +#ifdef CONFIG_HAVE_FSP + /* Store the HOB list if we have one */ + test %esi, %esi + jz skip_hob + movl %esi, GD_HOB_LIST(%edx) -#if defined(CONFIG_SYS_MALLOC_F_LEN) - subl $CONFIG_SYS_MALLOC_F_LEN, %esp - movl %eax, %edx - addl $GD_MALLOC_BASE, %edx - movl %esp, (%edx) + /* + * After fsp_init() returns, the stack has already been switched to a + * place within system memory as defined by CONFIG_FSP_TEMP_RAM_ADDR. + * Enlarge the size of malloc() pool before relocation since we have + * plenty of memory now. + */ + subl $CONFIG_FSP_SYS_MALLOC_F_LEN, %esp + movl %esp, GD_MALLOC_BASE(%edx) +skip_hob: +#else + /* Store table pointer */ + movl %esi, GD_TABLE(%edx) #endif /* Store BIST */ - movl %eax, %edx - addl $GD_BIST, %edx - movl %ebp, (%edx) - - /* Set second parameter to setup_gdt */ - movl %ecx, %edx - - /* Setup global descriptor table so gd->xyz works */ - call setup_gdt + movl %ebp, GD_BIST(%edx) /* Set parameter to board_init_f() to boot flags */ post_code(POST_START_DONE) xorl %eax, %eax - /* Enter, U-boot! */ + /* Enter, U-Boot! */ call board_init_f /* indicate (lack of) progress */ @@ -174,37 +192,7 @@ board_init_f_r_trampoline: /* Stack grows down from top of SDRAM */ movl %eax, %esp - /* Reserve space on stack for global data */ - subl $GENERATED_GBL_DATA_SIZE, %esp - - /* Align global data to 16-byte boundary */ - andl $0xfffffff0, %esp - - /* Setup first parameter to memcpy (and setup_gdt) */ - movl %esp, %eax - - /* Setup second parameter to memcpy */ - fs movl 0, %edx - - /* Set third parameter to memcpy */ - movl $GENERATED_GBL_DATA_SIZE, %ecx - - /* Copy global data from CAR to SDRAM stack */ - call memcpy - - /* Reserve space for global descriptor table */ - subl $X86_GDT_SIZE, %esp - - /* Align global descriptor table to 16-byte boundary */ - andl $0xfffffff0, %esp - - /* Set second parameter to setup_gdt */ - movl %esp, %edx - - /* Setup global descriptor table so gd->xyz works */ - call setup_gdt - - /* Set if we need to disable CAR */ + /* See if we need to disable CAR */ .weak car_uninit movl $car_uninit, %eax cmpl $0, %eax @@ -212,7 +200,7 @@ board_init_f_r_trampoline: call car_uninit 1: - /* Re-enter U-Boot by calling board_init_f_r */ + /* Re-enter U-Boot by calling board_init_f_r() */ call board_init_f_r die: @@ -226,9 +214,10 @@ blank_idt_ptr: .p2align 2 /* force 4-byte alignment */ + /* Add a multiboot header so U-Boot can be loaded by GRUB2 */ multiboot_header: /* magic */ - .long 0x1BADB002 + .long 0x1badb002 /* flags */ .long (1 << 16) /* checksum */ @@ -243,3 +232,71 @@ multiboot_header: .long 0 /* entry addr */ .long CONFIG_SYS_TEXT_BASE + +#ifdef 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 + * GDT is setup in a safe location in RAM + */ +gdt_ptr2: + .word 0x1f /* limit (31 bytes = 4 GDT entries - 1) */ + .long gdt_rom2 /* base */ + + /* Some CPUs are picky about GDT alignment... */ + .align 16 +.globl gdt_rom2 +gdt_rom2: + /* + * The GDT table ... + * + * Selector Type + * 0x00 NULL + * 0x08 Unused + * 0x10 32bit code + * 0x18 32bit data/stack + */ + /* The NULL Desciptor - Mandatory */ + .word 0x0000 /* limit_low */ + .word 0x0000 /* base_low */ + .byte 0x00 /* base_middle */ + .byte 0x00 /* access */ + .byte 0x00 /* flags + limit_high */ + .byte 0x00 /* base_high */ + + /* Unused Desciptor - (matches Linux) */ + .word 0x0000 /* limit_low */ + .word 0x0000 /* base_low */ + .byte 0x00 /* base_middle */ + .byte 0x00 /* access */ + .byte 0x00 /* flags + limit_high */ + .byte 0x00 /* base_high */ + + /* + * The Code Segment Descriptor: + * - Base = 0x00000000 + * - Size = 4GB + * - Access = Present, Ring 0, Exec (Code), Readable + * - Flags = 4kB Granularity, 32-bit + */ + .word 0xffff /* limit_low */ + .word 0x0000 /* base_low */ + .byte 0x00 /* base_middle */ + .byte 0x9b /* access */ + .byte 0xcf /* flags + limit_high */ + .byte 0x00 /* base_high */ + + /* + * The Data Segment Descriptor: + * - Base = 0x00000000 + * - Size = 4GB + * - Access = Present, Ring 0, Non-Exec (Data), Writable + * - Flags = 4kB Granularity, 32-bit + */ + .word 0xffff /* limit_low */ + .word 0x0000 /* base_low */ + .byte 0x00 /* base_middle */ + .byte 0x93 /* access */ + .byte 0xcf /* flags + limit_high */ + .byte 0x00 /* base_high */ +#endif