x86: Add various minor tidy-ups to the 32-bit startup code
Fix a typo, improve some comments and add a little more detail in some cases. Signed-off-by: Simon Glass <sjg@chromium.org> Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
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Simon Glass
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@ -25,11 +25,11 @@
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.globl _x86boot_start
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_x86boot_start:
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/*
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* This is the fail safe 32-bit bootstrap entry point. The
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* following code is not executed from a cold-reset (actually, a
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* lot of it is, but from real-mode after cold reset. It is
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* repeated here to put the board into a state as close to cold
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* reset as necessary)
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* This is the fail-safe 32-bit bootstrap entry point.
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*
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* This code is used when booting from another boot loader like
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* coreboot or EFI. So we repeat some of the same init found in
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* start16.
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*/
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cli
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cld
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@ -45,15 +45,15 @@ _x86boot_start:
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jmp 1f
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_start:
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/*
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* This is the 32-bit cold-reset entry point. Initialize %bx to 0
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* in case we're preceeded by some sort of boot stub.
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* This is the 32-bit cold-reset entry point, coming from start16.
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* Set %bx to 0 to indicate this.
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*/
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movw $GD_FLG_COLD_BOOT, %bx
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1:
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/* Save BIST */
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movl %eax, %ebp
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/* Load the segement registes to match the gdt loaded in start16.S */
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/* Load the segement registers to match the GDT loaded in start16.S */
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movl $(X86_GDT_ENTRY_32BIT_DS * X86_GDT_ENTRY_SIZE), %eax
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movw %ax, %fs
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movw %ax, %ds
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@ -64,7 +64,11 @@ _start:
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/* Clear the interrupt vectors */
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lidt blank_idt_ptr
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/* Early platform init (setup gpio, etc ) */
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/*
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* Critical early platform init - generally not used, we prefer init
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* to happen later when we have a console, in case something goes
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* wrong.
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*/
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jmp early_board_init
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.globl early_board_init_ret
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early_board_init_ret:
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@ -79,7 +83,7 @@ car_init_ret:
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* We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM,
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* or fully initialised SDRAM - we really don't care which)
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* starting at CONFIG_SYS_CAR_ADDR to be used as a temporary stack
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* and early malloc area. The MRC requires some space at the top.
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* and early malloc() area. The MRC requires some space at the top.
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*
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* Stack grows down from top of CAR. We have:
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*
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@ -97,7 +101,7 @@ car_init_ret:
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#endif
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#else
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/*
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* When we get here after car_init, esp points to a temporary stack
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* When we get here after car_init(), esp points to a temporary stack
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* and esi holds the HOB list address returned by the FSP.
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*/
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#endif
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@ -137,17 +141,18 @@ skip_hob:
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movl %esp, %ecx
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#if defined(CONFIG_SYS_MALLOC_F_LEN)
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/* Set up the pre-relocation malloc pool */
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subl $CONFIG_SYS_MALLOC_F_LEN, %esp
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movl %eax, %edx
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addl $GD_MALLOC_BASE, %edx
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movl %esp, (%edx)
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#endif
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/* Store BIST */
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/* Store BIST into global_data */
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movl %eax, %edx
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addl $GD_BIST, %edx
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movl %ebp, (%edx)
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/* Set second parameter to setup_gdt */
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/* Set second parameter to setup_gdt() */
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movl %ecx, %edx
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/* Setup global descriptor table so gd->xyz works */
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@ -157,7 +162,7 @@ skip_hob:
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post_code(POST_START_DONE)
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xorl %eax, %eax
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/* Enter, U-boot! */
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/* Enter, U-Boot! */
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call board_init_f
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/* indicate (lack of) progress */
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@ -184,13 +189,13 @@ board_init_f_r_trampoline:
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/* Align global data to 16-byte boundary */
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andl $0xfffffff0, %esp
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/* Setup first parameter to memcpy (and setup_gdt) */
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/* Setup first parameter to memcpy() and setup_gdt() */
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movl %esp, %eax
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/* Setup second parameter to memcpy */
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/* Setup second parameter to memcpy() */
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fs movl 0, %edx
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/* Set third parameter to memcpy */
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/* Set third parameter to memcpy() */
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movl $GENERATED_GBL_DATA_SIZE, %ecx
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/* Copy global data from CAR to SDRAM stack */
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@ -202,7 +207,7 @@ board_init_f_r_trampoline:
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/* Align global descriptor table to 16-byte boundary */
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andl $0xfffffff0, %esp
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/* Set second parameter to setup_gdt */
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/* Set second parameter to setup_gdt() */
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movl %esp, %edx
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/* Setup global descriptor table so gd->xyz works */
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@ -216,7 +221,7 @@ board_init_f_r_trampoline:
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call car_uninit
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1:
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/* Re-enter U-Boot by calling board_init_f_r */
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/* Re-enter U-Boot by calling board_init_f_r() */
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call board_init_f_r
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die:
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@ -230,9 +235,10 @@ blank_idt_ptr:
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.p2align 2 /* force 4-byte alignment */
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/* Add a multiboot header so U-Boot can be loaded by GRUB2 */
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multiboot_header:
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/* magic */
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.long 0x1BADB002
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.long 0x1badb002
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/* flags */
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.long (1 << 16)
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/* checksum */
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