[U-Boot-Users] ppc405gp cpu problems

[Tadas]

Second problem  solved, seems cpu realy behave strangely,
I placed ram initialization at the very begining of bootloader and now it
works.
also there was some incorect timing but it is not likely to cause problem,
(becase fixing that did not helped)
ram just must be initialized before any other peripherials
(dont know why but now it works ok) at first the first thing initilalized
was UART.


>>>
>>> first problem with bootloader:
>>>...
>>> Seems everybody else is executing this code without problems

>Indeed. Are you sure your CPU can read  the  flash  contents  without
>problems?


The reson of this one is till unknown, but it does not matter, anyway.

I also found, that some time ago this instruction  also was removed on
ppcboot so someone
had this problem too.
http://cvs.tuxbox.org/cgi-bin/viewcvs.cgi/tuxbox/boot/ppcboot/ppc4xx/Attic/start.S?rev=1.2&content-type=text/vnd.viewcvs-markup

#if 1  /* test-only */
        addi    r4,r0,0x1000          // set ME bit (Machine Exceptions)
        oris    r4,r4,0x0002          // set CE bit (Critical Exceptions)
        mtmsr   r4                     // change MSR
#else   /* problems in rom2ram (see test-only in rom2ram!!!) */
        addi    r4,r0,0x0000          // dont set (!!!) ME bit (Machine
Exceptions)
        oris    r4,r4,0x0002          // set CE bit (Critical Exceptions)
        mtmsr   r4                     // change MSR
#endif
as you see it is same instruction.

It would be interesting to know why this happens.