[U-Boot] [PATCH 12/39] x86: Tidy up global descriptor table setup

[Simon Glass]

On 7 November 2014 02:37, Bin Meng <bmeng.cn at gmail.com> wrote:
> On Fri, Nov 7, 2014 at 4:20 AM, Simon Glass <sjg at chromium.org> wrote:
>> This code is a little muddled, so tidy it up. Make sure that we put the
>> GDT in the right place and set it up properly.
>>
>> Signed-off-by: Simon Glass <sjg at chromium.org>
>> ---
>>
>>  arch/x86/cpu/start.S | 19 ++++++++++++++++---
>>  1 file changed, 16 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/x86/cpu/start.S b/arch/x86/cpu/start.S
>> index 62ac4cd..c41e1ae 100644
>> --- a/arch/x86/cpu/start.S
>> +++ b/arch/x86/cpu/start.S
>> @@ -69,6 +69,16 @@ 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.
>> +        *
>> +        * Stack grows down from top of CAR. We have:
>> +        *
>> +        * top-> CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE
>> +        *      global_data
>> +        *      x86 global descriptor table
>> +        *      early malloc area
>> +        *      stack
>> +        * bottom-> CONFIG_SYS_CAR_ADDR
>>          */
>>
>>         /* Stack grows down from top of CAR */
>> @@ -86,12 +96,16 @@ car_init_ret:
>>         movl    %esp, %edi
>>         rep     stosb
>>
>> -       /* Setup first parameter to setup_gdt */
>> +       /* 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
>> +
>>  #if defined(CONFIG_SYS_MALLOC_F_LEN)
>>         subl    $CONFIG_SYS_MALLOC_F_LEN, %esp
>>         movl    %eax, %edx
>> @@ -103,14 +117,13 @@ car_init_ret:
>>         andl    $0xfffffff0, %esp
>>
>>         /* Set second parameter to setup_gdt */
>> -       movl    %esp, %edx
>> +       movl    %ecx, %edx
>>
>>         /* Setup global descriptor table so gd->xyz works */
>>         call    setup_gdt
>>
>>         /* Set parameter to board_init_f() to boot flags */
>>         xorl    %eax, %eax
>> -       movw    %bx, %ax
>>
>>         /* Enter, U-boot! */
>>         call    board_init_f
>> --
>
> Reviewed-by: Bin Meng <bmeng.cn at gmail.com>

Applied to u-boot-x86.