[ECOS] Re: Problem on allocate PCI memory space...

["Ling Su" <lingsu@palmmicro.com>]

> >
> > Program received signal SIGSEGV, Segmentation fault.
> > 0x80100bb8 in pci_test () at pcitest.c:293
> > 293     (*(pci_base + 0x004)) = 0x0000;
> >
> > Dump of assembler code from 0x80100ba6 to 0x80100bff:
> > 0x80100ba6 <pci_test+682>: daddiu $a0,$a0,-8908
> > 0x80100baa <pci_test+686>: jal 0x8010522c <diag_printf>
> > 0x80100bae <pci_test+690>: lw $a1,156($s8)
> > 0x80100bb2 <pci_test+694>: lw $v0,156($s8)
> > 0x80100bb6 <pci_test+698>: addiu $v0,$v0,4
> > 0x80100bba <pci_test+702>: sb $zero,0($v0)
>
> I would guess that this sb is the problem instruction. One thought is
> that the device is not happy with byte sized accesses. Maybe you need
> to do 16 bit or 32 bit accesses. This is certainly true of the
> configuration space.
>

I tried to access 32bit access, the result is the same. So this won't be the
problem.

> See my previous message about how to determine whether this is a TLB
> or an device problem.
>
> If you take a look at the registers and the specific instruction that
> the exception occured on you should be able to work out exactly what
> address it was trying to access, and the value in the cause register
> should tell you what exception it actually was. If it's a TLB
> exception then maybe the MMU setup needs changing, if its
> a bus exception then the problem lies in the hardware setup.
>

I checked the "cause" register, the value is 0x800C, which means the TLB
Miss Exception(store) occurs. I dobut if I only change the NUMB_PG to 16 the
TLB will be enough to handle 512MB space, could you please take a look at
the TLB part. I will also check this by myself.

Could you please explain the implementation of TLB in eCos a little bit for
me? Thanks!

Best Regards,
-Ling