having trouble installing exceptions

having trouble installing exceptions

[Mike Manchip]

Hi all

I'm currently trying to get the mips port to work on a galileo gt64115 board
with a rm5231 chip.

I'm OK right until the point when I'm installing exceptions into
non-cacheable space in arch/mips/kernel/traps.c

as soon as I memcpy except_vec3_generic to KSEG0 + 0x180 and flush the
instruction cache, my machine hangs, and I can't see why!


/* Copy the generic exception handler code to it's final destination. */
 memcpy((void *)(KSEG0 + 0x80), &except_vec1_generic, 0x80);
 memcpy((void *)(KSEG0 + 0x100), &except_vec2_generic, 0x80);
 memcpy((void *)(KSEG0 + 0x180), &except_vec3_generic, 0x80);
 flush_icache_range(KSEG0 + 0x80, KSEG0 + 0x200);

Is it possibly something to do with the monitor I'm using? I'm using both
PROM and in desperation, a vxworks one (it can see the ethernet card, thus
speeding up kernel loads tremendously).
How does the monitor do exceptions? Do I have to do something special with
exceptions when a monitor is present?

thanks
mike

Re: having trouble installing exceptions

[Ralf Baechle]

On Fri, Sep 28, 2001 at 01:54:43PM +0100, Mike Manchip wrote:

> I'm currently trying to get the mips port to work on a galileo gt64115 board
> with a rm5231 chip.
> 
> I'm OK right until the point when I'm installing exceptions into
> non-cacheable space in arch/mips/kernel/traps.c
> 
> as soon as I memcpy except_vec3_generic to KSEG0 + 0x180 and flush the
> instruction cache, my machine hangs, and I can't see why!

KSEG0 is normally cached space.  If of some reason it's configured as
non-cachable and you're flushing caches funny things will happen.

> /* Copy the generic exception handler code to it's final destination. */
>  memcpy((void *)(KSEG0 + 0x80), &except_vec1_generic, 0x80);
>  memcpy((void *)(KSEG0 + 0x100), &except_vec2_generic, 0x80);
>  memcpy((void *)(KSEG0 + 0x180), &except_vec3_generic, 0x80);
>  flush_icache_range(KSEG0 + 0x80, KSEG0 + 0x200);
> 
> Is it possibly something to do with the monitor I'm using? I'm using both
> PROM and in desperation, a vxworks one (it can see the ethernet card, thus
> speeding up kernel loads tremendously).
> How does the monitor do exceptions? Do I have to do something special with
> exceptions when a monitor is present?

So firmware is operating with BEV set, thus won't use the vectors at
KSEG0 at all.

  Ralf

Re: having trouble installing exceptions

[Jun Sun]

Mike Manchip wrote:
> 
> Hi all
> 
> I'm currently trying to get the mips port to work on a galileo gt64115 board
> with a rm5231 chip.
> 
> I'm OK right until the point when I'm installing exceptions into
> non-cacheable space in arch/mips/kernel/traps.c
> 
What do you mean by "non-cachable space"?  KSEG0 is cacheable by default.

> as soon as I memcpy except_vec3_generic to KSEG0 + 0x180 and flush the
> instruction cache, my machine hangs, and I can't see why!
>

Most likely it hangs in flush_icache_range().  Put some printk there.

Jun