Re: [ECOS] How to access PCI memory(HELP)....

[Nick Garnett <nickg at cygnus dot co dot uk>]

"Ling Su" <lingsu@palmmicro.com> writes:

> >
> > I responded to your previous message before I saw this one. As I said
> > there, I think that adjusting HAL_PHYSICAL_MEMORY_BASE so that the CPU
> > addr ends up at 0xD000_0000 will fix your problem.
> >
> > I guess HAL_PHYSICAL_MEMORY_BASE is probably misnamed, it should
> > really be HAL_PHYSICAL_MEMORY_OFFSET. It only works as a base when the
> > PCI memory allocation starts at zero.
> >
> Hi, Nick,
> 
> Yeah, I think I can understand your suggestion, unfortuantely I still met
> segment fault. I append my log message in the end, please take a look, I
> don't exactly the memory mapping for eCos in vrc4373 board. I guess there is
> something wrong on the PCI space and memory space. Could you let me know how
> can I trace the SIGSEGV and the segment fault, so that I can figure out
> which part is wrong. I don't quiet understand why I can not access
> 0xD000_0000 at all.
> 
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.


-- 
Nick Garnett, eCos Kernel Architect
Red Hat, Cambridge, UK