Problem with jumping from assembly to c function

Hi stefan

For my previous mail of cross compiling the kernel for mips
board. I resolved the issue
As u mentioned of on HOSTCC and CC for Target.

Is there any other way of compiling forth sources. If so how to
eliminate the Hosted compilation
Directory i.e. unix directory which is in kernel-1.1/arch/unix.

And after cross compilation I am facing the problem of jumping from
boot.s to main. Somehow
Succeeded in jumping to cmain function. Openbios function is called from
cmain during this period
Context is saved is it necessary to initialize global pointer. Because
once it goes to cmain after some
Execution of instructions the global pointer gets manipulated and
exception occurs. Why is it so.

For example

Boot.s contains this

RAM address   Mnemonics	Instructions

a0100044:       3c1ca011        lui     gp,0xa011
/* Loads the global pointer address */
    a0100048:       279c40c8        addiu   gp,gp,16584
    a010004c:       8f8880a4        lw      t0,-32604(gp)	/* get
the address of cmain which is stored in to (temp register) */
    a0100050:       01000008        jr      t0
/* jumps to main */

a0100070 <cmain>:
    a0100070:       3c1c0001        lui     gp,0x1		/* don't
know why gp is loaded with 0x1 */
    a0100074:       279c4058        addiu   gp,gp,16472
    a0100078:       0399e021        addu    gp,gp,t9
    a010007c:       27bdffe0        addiu   sp,sp,-32
    a0100080:       afbc0010        sw      gp,16(sp)
    a0100084:       8f848010        lw      a0,-32752(gp)

/* after this instruction exception is occuring and jumping to
0x80000000 address (RAM) */
    a0100088:       00000000        nop

But in /arch/x86 example there is only the initilization of stack
pointer. Do u have any example for
Cross compilation procedure and linking the linker script to download to
ROM or RAM.

Regards
Viswanath

[Patrick Mauritz]

Am Mittwoch, 8. September 2004 12:03 schrieb [e-mail]:
> Is there any other way of compiling forth sources. If so how to
> eliminate the Hosted compilation
> Directory i.e. unix directory which is in kernel-1.1/arch/unix.

you seem to be using a pretty old version ("kernel-1.1" indicates this). check 
at http://openbios.org/snapshots/ for recent snapshots
> But in /arch/x86 example there is only the initilization of stack
> pointer. Do u have any example for
> Cross compilation procedure and linking the linker script to download to
> ROM or RAM.

crosscompile support is still marginal - I'll take a look at integrating it 
properly over the next days.

patrick mauritz

[Stefan Reinauer]

Hi Viswanath,

* [e-mail]  [040908 12:03]:
> For my previous mail of cross compiling the kernel for mips
> board. I resolved the issue
> As u mentioned of on HOSTCC and CC for Target.
>
> Is there any other way of compiling forth sources.

You can choose a system with the same bit width (32/64bit) and and
endianess (big/little endian) and compile the dictionary natively there.
Otherwise you will have to wait until OpenBIOS supports cross compiling
officially.
> And after cross compilation I am facing the problem of jumping from
> boot.s to main. Somehow
> Succeeded in jumping to cmain function. Openbios function is called from
> cmain during this period
> Context is saved is it necessary to initialize global pointer. Because
> once it goes to cmain after some
> Execution of instructions the global pointer gets manipulated and
> exception occurs. Why is it so.

Do you get any output before this? Did you initialize the stack properly
in or before boot.S?
> But in /arch/x86 example there is only the initilization of stack
> pointer. Do u have any example for
> Cross compilation procedure and linking the linker script to download to
> ROM or RAM.

Have a look at the current version at http://www.openbios.org/snapshots/

Relocation from rom to ram is currently only done by the underlying ELF
loader (ie LinuxBIOS) but we want to support more in the future. Any
concrete ideas / patches are welcome.

Stefan