X-Git-Url: https://git.sur5r.net/?a=blobdiff_plain;f=arch%2Fx86%2Fcpu%2Fstart.S;h=e94ddc45ddb78475eefa3e306b9f352d1f378755;hb=f0c7d9c74642ccd6c76993b721b0fb87aab685fa;hp=f51f1121d0252b3b96f856bac574bc6b19fff6ce;hpb=306df2c8241bd363c71a99841630fb5e85d81fae;p=u-boot diff --git a/arch/x86/cpu/start.S b/arch/x86/cpu/start.S index f51f1121d0..e94ddc45dd 100644 --- a/arch/x86/cpu/start.S +++ b/arch/x86/cpu/start.S @@ -11,7 +11,6 @@ */ #include -#include #include #include #include @@ -26,11 +25,11 @@ .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 @@ -42,19 +41,34 @@ _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: - /* Load the segement registes to match the gdt loaded in start16.S */ + /* Save table pointer */ + movl %ecx, %esi + + /* 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 @@ -65,7 +79,11 @@ _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: @@ -80,14 +98,13 @@ 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 @@ -98,63 +115,45 @@ car_init_ret: #endif #else /* - * When we get here after car_init, esp points to a temporary stack + * When we get here after car_init(), esp points to a temporary stack * and esi holds the HOB list address returned by the FSP. */ #endif + /* Set up global data */ + mov %esp, %eax + call board_init_f_mem + mov %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 - 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 + /* + * Debug UART is available here although it may not be plumbed out + * to pins depending on the board. To use it: + * + * call debug_uart_init + * mov $'a', %eax + * call printch + */ + /* Get address of global_data */ + mov %fs:0, %edx #ifdef CONFIG_HAVE_FSP - /* Store HOB list */ - movl %esp, %edx - addl $GD_HOB_LIST, %edx - movl %esi, (%edx) -#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 + /* Store the HOB list if we have one */ + test %esi, %esi + jz skip_hob + movl %esi, GD_HOB_LIST(%edx) - /* Align temporary global descriptor table to 16-byte boundary */ - andl $0xfffffff0, %esp - movl %esp, %ecx - -#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) +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 */ @@ -175,37 +174,7 @@ 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 @@ -213,7 +182,7 @@ 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: @@ -227,9 +196,10 @@ 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 */