Help Needed.

[sivakumar]

Hi,

I want to understand the flow of the following piece fo the code. It is
for copying the Linuxbios image from Flash ROM to RAM.

Here I want to what is the value of the _liseg, _iseg, _eliseg  segment
address. Can any one explain the following code.

My system hangs in this part of code (i.e. at rep and movsb instruction.
As per the Ron's SUGGESTION I also used spd to get the value for RAM
intialization.

But still it loop at this point

jz      .Lnocopy
        movl    $EXT(_eliseg), %ecx
        CONSOLE_DEBUG_TX_HEX32(%ecx)
        subl    %esi, %ecx
        jz      .Lnocopy                /* should not happen */
        rep
        movsb
        CONSOLE_DEBUG_TX_STRING($siva_debug5)
.Lnocopy:

Thanks,
Siva.S

/*
         *      Copy data into RAM and clear the BSS. Since these
segments
         *      isn't really that big we just copy/clear using bytes,
not
         *      double words.
         */
        CONSOLE_DEBUG_TX_STRING($siva_debug1)
        intel_chip_post_macro(0x11)             /* post 11 */

cld                             /* clear direction flag */

/* copy linuxBIOS from it's initial load location to
         * the location it is compiled to run at.
         * Normally this is copying from FLASH ROM to RAM.
         */
        leal    EXT(_liseg), %esi
        leal    EXT(_iseg), %edi
        cmpl    %esi, %edi
        jz      .Lnocopy
        movl    $EXT(_eliseg), %ecx
        CONSOLE_DEBUG_TX_HEX32(%ecx)
        subl    %esi, %ecx
        jz      .Lnocopy                /* should not happen */
        rep
        movsb
        CONSOLE_DEBUG_TX_STRING($siva_debug5)
.Lnocopy:
        CONSOLE_DEBUG_TX_STRING($siva_debug6)
        intel_chip_post_macro(0x12)             /* post 12 */

/** clear stack */
        leal    EXT(_stack), %edi
        movl    $EXT(_estack), %ecx
        subl    %edi, %ecx
        xorl    %eax, %eax
        rep
        stosb

/** clear bss */
        leal    EXT(_bss), %edi
        movl    $EXT(_ebss), %ecx
        subl    %edi, %ecx
        jz      .Lnobss
        xorl    %eax, %eax
        rep
        stosb

[Ronald G. Minnich]

I would suggest you use the dumpnorth code in:
 src/bios/freebios/src/ram/dump_northbridge.inc

and check each step of your northbridge configuration.

To do this, in your config you will have this in your config:
mainboardinit ram/dump_northbridge.inc

To use it:

CALLSP(dumpnorth)

at various places.

the file src/bios/freebios/src/northbridge/intel/430tx/raminit.inc
shows some uses of this function. We found it very handy for getting that 
part up.

ron

[Ivan Pulleyn]

Hi, This may have nothing to do with your questions, but shouldn't
there be a 'cld' statement before the 'rep movsb'?

Ivan...

On 2 Jan 2003, sivakumar wrote:
> Hi,
>
> I want to understand the flow of the following piece fo the code. It is
> for copying the Linuxbios image from Flash ROM to RAM.
>
> Here I want to what is the value of the _liseg, _iseg, _eliseg  segment
> address. Can any one explain the following code.
>
> My system hangs in this part of code (i.e. at rep and movsb instruction.
> As per the Ron's SUGGESTION I also used spd to get the value for RAM
> intialization.
>
> But still it loop at this point
>
> jz      .Lnocopy
>         movl    $EXT(_eliseg), %ecx
>         CONSOLE_DEBUG_TX_HEX32(%ecx)
>         subl    %esi, %ecx
>         jz      .Lnocopy                /* should not happen */
>         rep
>         movsb
>         CONSOLE_DEBUG_TX_STRING($siva_debug5)
> .Lnocopy:
>
> Thanks,
> Siva.S
>
> /*
>          *      Copy data into RAM and clear the BSS. Since these
> segments
>          *      isn't really that big we just copy/clear using bytes,
> not
>          *      double words.
>          */
>         CONSOLE_DEBUG_TX_STRING($siva_debug1)
>         intel_chip_post_macro(0x11)             /* post 11 */
>     cld                             /* clear direction flag */
>
>     /* copy linuxBIOS from it's initial load location to
>      * the location it is compiled to run at.
>      * Normally this is copying from FLASH ROM to RAM.
>      */
>     leal    EXT(_liseg), %esi
>     leal    EXT(_iseg), %edi
>     cmpl    %esi, %edi
>     jz      .Lnocopy
>     movl    $EXT(_eliseg), %ecx
>     CONSOLE_DEBUG_TX_HEX32(%ecx)
>     subl    %esi, %ecx
>     jz      .Lnocopy                /* should not happen */
>     rep
>     movsb
>     CONSOLE_DEBUG_TX_STRING($siva_debug5)
>
> .Lnocopy:
>         CONSOLE_DEBUG_TX_STRING($siva_debug6)
>         intel_chip_post_macro(0x12)             /* post 12 */
>     /** clear stack */
>     leal    EXT(_stack), %edi
>     movl    $EXT(_estack), %ecx
>     subl    %edi, %ecx
>     xorl    %eax, %eax
>     rep
>     stosb
>
>     /** clear bss */
>     leal    EXT(_bss), %edi
>     movl    $EXT(_ebss), %ecx
>     subl    %edi, %ecx
>     jz      .Lnobss
>     xorl    %eax, %eax
>     rep
>     stosb