memory corruption after MMU turned on

[Lei Sun]

I tried enable i-cache, but it looks fine, however if i enable
d-cache, u-boot corrupted right away, debugger showed some garbage
memory instead of valid instruction.

Thanks
lei

On 11/18/06, Dave Liu <r63238 at freescale.com> wrote:
> Did you enable the i-cache or d-cache in u-boot? if you enable i-cache,
> I think the core are burst reading from memory.
>
> On Fri, 2006-11-17 at 11:47 -0500, Lei Sun wrote:
> > No, i didn't do the burst memory test, how do i do it then ?
> >
> > On 11/17/06, Dave Liu <r63238 at freescale.com> wrote:
> > > On Thu, 2006-11-16 at 10:44 -0500, Lei Sun wrote:
> > > > Hi all:
> > > >    I am trying to bring up customized board based on MPC8270, the
> > > > kernel version is 2.4.30, it works fine on one of the Eval board
> > > > (PQ2FADS-VR, which use MPC8275).
> > > >    The kernel hangs after uncompressing is done, further debug shows
> > > > that it hangs right after "rfi " instruction of the turn_on_mmu:
> > > > function in head.S
> > > >
> > > >  turn_on_mmu:
> > > >     240     mfmsr   r0
> > > >     241     ori r0,r0,MSR_DR|MSR_IR
> > > >     242     mtspr   SRR1,r0
> > > >     243     lis r0,start_here at h
> > > >     244     ori r0,r0,start_here at l
> > > >     245     mtspr   SRR0,r0
> > > >     246     SYNC
> > > >     247     RFI             /* enables MMU */
> > > >
> > > > After i step over the RFI instruction, the PC points to C000XXX , but
> > > > all memory content is 0 by then.
> > > > my BATU0 is 0xC000FFE0  BATL0 is 0x00000002, I have 128MB RAM. The
> > > > u-boot works fine, without MMU turned on. We do have some hardware
> > > > problem, such that i have to lower the bus frequency to make the SDRAM
> > > > stable. What physical parameter could cause the board not working with
> > > > MMU on?
> > >
> > > When MMU turn on, the kernel memory should be cacheable, so the
> > > processor will burst read instructions from memory to i-cache. Did you
> > > do the burst read/write memory test in u-boot? As you said, you did not
> > > do the test.
> > >
> > > -Dave
> > >
> > >
> > >
>
>