Re: [U-Boot] [PATCH 08/48] x86: Add various minor tidy-ups to the 32-bit startup code

On Wed, Jul 22, 2015 at 11:49 PM, Simon Glass sjg@chromium.org wrote:

Fix a typo, improve some comments and add a little more detail in some cases.

Signed-off-by: Simon Glass sjg@chromium.org

arch/x86/cpu/start.S | 46 ++++++++++++++++++++++++++-------------------- 1 file changed, 26 insertions(+), 20 deletions(-)

diff --git a/arch/x86/cpu/start.S b/arch/x86/cpu/start.S index 00e585e..7ef8b88 100644 --- a/arch/x86/cpu/start.S +++ b/arch/x86/cpu/start.S @@ -25,11 +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
  

@@ -45,15 +45,15 @@ _x86boot_start: jmp 1f _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 %bx to 0 to indicate this.
     */
    movw    $GD_FLG_COLD_BOOT, %bx
  

1: /* Save BIST */ movl %eax, %ebp

•   /* Load the segement registes to match the gdt loaded in start16.S */
  

•   /* 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 +64,11 @@ _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: @@ -79,7 +83,7 @@ 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:
     *
  

@@ -97,7 +101,7 @@ 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 @@ -137,17 +141,18 @@ skip_hob: movl %esp, %ecx

#if defined(CONFIG_SYS_MALLOC_F_LEN)

•   /* Set up the pre-relocation malloc pool */
    subl    $CONFIG_SYS_MALLOC_F_LEN, %esp
    movl    %eax, %edx
    addl    $GD_MALLOC_BASE, %edx
    movl    %esp, (%edx)
  

#endif

•   /* Store BIST */
  

•   /* Store BIST into global_data */
    movl    %eax, %edx
    addl    $GD_BIST, %edx
    movl    %ebp, (%edx)
  
  

•   /* Set second parameter to setup_gdt */
  

•   /* Set second parameter to setup_gdt() */
    movl    %ecx, %edx
  
    /* Setup global descriptor table so gd->xyz works */
  

@@ -157,7 +162,7 @@ skip_hob: post_code(POST_START_DONE) xorl %eax, %eax

•   /* Enter, U-boot! */
  

•   /* Enter, U-Boot! */
    call    board_init_f
  
    /* indicate (lack of) progress */
  

@@ -184,13 +189,13 @@ board_init_f_r_trampoline: /* Align global data to 16-byte boundary */ andl $0xfffffff0, %esp

•   /* Setup first parameter to memcpy (and setup_gdt) */
  

•   /* Setup first parameter to memcpy() and setup_gdt() */
    movl    %esp, %eax
  
  

•   /* Setup second parameter to memcpy */
  

•   /* Setup second parameter to memcpy() */
    fs movl 0, %edx
  
  

•   /* Set third parameter to memcpy */
  

•   /* Set third parameter to memcpy() */
    movl    $GENERATED_GBL_DATA_SIZE, %ecx
  
    /* Copy global data from CAR to SDRAM stack */
  

@@ -202,7 +207,7 @@ board_init_f_r_trampoline: /* Align global descriptor table to 16-byte boundary */ andl $0xfffffff0, %esp

•   /* Set second parameter to setup_gdt */
  

•   /* Set second parameter to setup_gdt() */
    movl    %esp, %edx
  
    /* Setup global descriptor table so gd->xyz works */
  

@@ -216,7 +221,7 @@ 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: @@ -230,9 +235,10 @@ 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 */
  

--

Reviewed-by: Bin Meng bmeng.cn@gmail.com