[U-Boot-Users] u-boot hangs in ./cpu/mpc8xx/cpu_init.c when changing br0

[Jeff Mann]

>You did read http://www.denx.de/wiki/view/DULG/DebuggingTricks , didn't
you?

I did, but those compiler flags were in by board directory, I moved them
to the makefile in the top directory, and this simplifies watching the
code.

But back to the problem.

./cpu/mpc8xx/cpu_init.c

In "C":
 118         reg = memctl->memc_br0;
 119         reg &= BR_PS_MSK;       /* Clear everything except Port
Size bits */
 120         reg |= BR_V;            /* then add just the "Bank Valid"
bit     */
 121         memctl->memc_br0 = reg;

In Assembly, this compiles to:
Ln 118    0xff007ce4 <cpu_init_f+172>:    lwz     r0,0(r28)
Ln 119    0xff007ce8 <cpu_init_f+176>:    rlwinm  r0,r0,0,20,21
Ln 120    0xff007cec <cpu_init_f+180>:    ori     r0,r0,1
Ln 121    0xff007cf0 <cpu_init_f+184>:    stw     r0,0(r28)

r28 holds the value 0xfa200100 (the location of br0)
At line 118, br0 is loaded into r0. r0 then holds 0xfc000001.
At line 119, r0 becomes 0x00000000. <<-- This is the problem, I think
At line 120, r0 becomes 0x00000001
At line 121, r0 is saved to br0 (the address pointed to by r28). 
(br0 becomes 0x00000001)

in ./include/mpc8xx.h:
  #define  BR_PS_MSK  0x00000C00 
Is this right?

The program fails at ln 180 with:
"Program received signal SIGABRT, aborted."
But by this time, br0 was reloaded with CFG_BR0_PRELIM from line 176. 

Any more ideas?
Thanks,
JM

-----Original Message-----
From: wd at denx.de [mailto:wd at denx.de] 
Sent: Tuesday, June 20, 2006 5:53 PM
To: Jeff Mann
Cc: u-boot-users at lists.sourceforge.net
Subject: Re: [U-Boot-Users] u-boot hangs in ./cpu/mpc8xx/cpu_init.c when
changing br0 

In message
<1628E43D99629C46988BE46087A3FBB95C57DD at ep-01.EmbeddedPlanet.local> you
wrote:
> 
> reg does not get the value of br0 at line 118, like it should. In 
> fact, DDD acts like the variable does not even exist. So at line 121, 
> br0 is
...
> Any suggestions?

You did read http://www.denx.de/wiki/view/DULG/DebuggingTricks , didn't
you?

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 denx.de
The light at the end of the tunnel is usually a "No Exit" sign.