reboot on PQ2FADS board.

Wolfgang Denk wd at
Wed Jul 19 16:33:17 EST 2006

In message <4879B0C6C249214CBE7AB04453F84E4D050B0F at> you wrote:
> > command cause machine check and kernel ooops.  The problem seems in
> > the "m8260_gorom" in head.S.  The restart() function in m8260_setup.c
> > passed 2 parameters to that assembly code, r3 is the bd_info , r4 is
> > the warm start address,  I changed it to 0xFF800100, that's where the
> > u-boot's _start_warm lives, I have verified that address by typing "g
> > ff800100" in u-boot console, which cause the board reset.
> Are you sure ff800100 is _start_warm lives?  In latest u-boot

Trying to jump to some boot rom address is IMHO always a bad approach
to reboot a system. You should always try to cause a reset  condition
for  the CPU, and thus for all the associated hardware. On 8xx / 8260
systems this is usually done by going through  a  machine  check.  We
have  the  following code in our linuxppc_2_4_devel tree, which works
on ALL 8260 systems, no matter whioch boot loder they use:

static void
m8260_restart(char *cmd)
        __volatile__ unsigned char dummy;
        ulong msr;
        volatile immap_t *immap = (immap_t *) IMAP_ADDR;
        immap->im_clkrst.car_rmr = 1;    /* Checkstop Reset enable */
        /* Interrupts and MMU off */
        __asm__ __volatile__ ("mfmsr    %0":"=r" (msr):);
        msr &= ~(MSR_ME | MSR_EE | MSR_IR | MSR_DR);
        __asm__ __volatile__ ("mtmsr    %0"::"r" (msr)); 
        dummy = ((immap_t *)IMAP_ADDR)->im_clkrst.res[0];
        printk("Restart failed\n");
        for (;;);

Best regards,

Wolfgang Denk

Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at
If a group of N persons implements a COBOL compiler,  there  will  be
N-1 passes. Someone in the group has to be the manager. - T. Cheatham

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