[U-Boot-Users] weird power-on reset problem

[U-Boot-Users] weird power-on reset problem

[Jerry Van Baren]

Read your 860 manual Chapter 12.  Three times.  The difference between a 
power on reset (PORESET*) and a pushbutton (hardware reset or software 
induced reset) involves reading the configuration off the data bus and 
starting the clocks (PLL).

When power is applied, the processor reads the configuration, sets up the 
PLLs, and lets them stabilize.  On a pushbutton reset, the processor does 
NOT read the configuration and the clocks keep running however they were 
configured when power was applied.

I would be very suspicious that your PLLs are not stabilizing in 
time.  This would most likely be due to an unstable input clock or possibly 
due to unstable or noisy power supply voltages.

 From the 860 maunual, Chapter 12:

"When PORESET signal is negated, the MODCK values are sampled and internally
latched. To ensure proper operation, the PORESET signal should be asserted 
for a
minimum of 3 microseconds."

Question: Does your hardware ensure this?

"When a hard reset event occurs, the MPC860 determines its initial mode of 
operation by
sampling the values present on the data bus (D[0?31])..."

Question: Does your hardware ensure the data bus lines are driven properly 
until after the initial mode of operation is established?  Note that the 
manual says the processor leaves the reset state after PORESET is released 
_AND_ the PLLs are stable.  PLL instability could stretch your start up 
time, causing problems.

Question: Is your RSTCONF* being driven properly?

gvb


At 02:50 PM 1/17/2003 -0500, bren at sjtu.edu.cn wrote:
>We have a very very weird problem.
>When we power-on our MPC860 board, u-boot will stuck
>before running in RAM. But once we reset the board
>with the "reset push button", everything will be fine
>as long as we DO NOT power-off.
>
>Obviously, there are some differences between power-on
>reset and internal hardware reset and those differences
>are where we make some mistakes.
>
>Can anyone help us?
>
>Thanks.
>
>Laudney Ren
>
>--
>An expert is one who knows more and more about less and less
>until he knows absolutely everything about nothing.
>
>
>
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[U-Boot-Users] Offset beginning of flash image?

[Timothy Canham]

I am trying to load two boot loaders on to the flash at once. We want to 
put the vxworks bootloader first, then jump to the beginning of the 
ppcboot loader at a higher address in the flash when we need to. What 
parameters do I need to change to to allow this? I found the TEXT_BASE 
in config.mk. Is there anywhere else?

-- 
Timothy K. Canham
Jet Propulsion Laboratory
Pasadena, CA
Timothy.Canham at jpl.nasa.gov
MDS Flight Software

[U-Boot-Users] Offset beginning of flash image?

[Wolfgang Denk]

In message <3E2873F9.5050107@jpl.nasa.gov> you wrote:
> I am trying to load two boot loaders on to the flash at once. We want to 
> put the vxworks bootloader first, then jump to the beginning of the 
> ppcboot loader at a higher address in the flash when we need to. What 

This will not work. PPCBoot  /  U-Boot  expect  to  find  a  "virgin"
system, i. e. to be started from the reset entry point.


I don't say it can't be done, but you have to understand exactly  how
the  initialization sequence works, and what already has been done by
your other boot loader.


I recommend to use just U-Boot,  and  dump  the  VxWorks  bootloader.
U-Boot can boot VxWorks fine, too.


Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
Consultants are mystical people who ask a company for  a  number  and
then give it back to them.

[U-Boot-Users] Offset beginning of flash image?

[Timothy Canham]

The problem is that PPCBoot doesn't support the rsh method of booting 
kernels, so we are stuck w/ tftpboot. We can't use that for our vxworks 
kernels.

Wolfgang Denk wrote:

>In message <3E2873F9.5050107@jpl.nasa.gov> you wrote:
>  
>
>>I am trying to load two boot loaders on to the flash at once. We want to 
>>put the vxworks bootloader first, then jump to the beginning of the 
>>ppcboot loader at a higher address in the flash when we need to. What 
>>    
>>
>
>This will not work. PPCBoot  /  U-Boot  expect  to  find  a  "virgin"
>system, i. e. to be started from the reset entry point.
>
>
>I don't say it can't be done, but you have to understand exactly  how
>the  initialization sequence works, and what already has been done by
>your other boot loader.
>
>
>I recommend to use just U-Boot,  and  dump  the  VxWorks  bootloader.
>U-Boot can boot VxWorks fine, too.
>
>
>Best regards,
>
>Wolfgang Denk
>
>  
>

-- 
Timothy K. Canham
Jet Propulsion Laboratory
Pasadena, CA
Timothy.Canham at jpl.nasa.gov
MDS Flight Software


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[U-Boot-Users] Offset beginning of flash image?

[Wolfgang Denk]

In message <3E288496.3090600@jpl.nasa.gov> you wrote:
> 
> The problem is that PPCBoot doesn't support the rsh method of booting 
> kernels, so we are stuck w/ tftpboot. We can't use that for our vxworks 
> kernels.

Well, I don't know what VxWorks "rsh method" is, but if it  _is_  rsh
then  you  need  a  full TCP/IP stack, while U-Boot comes just with a
minimal subset of UDP.

Why cannot you use TFTP? As it is the more primitive thing to  do  it
should be easier, too...

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
Dealing with failure is easy: work hard to improve. Success  is  also
easy  to  handle:  you've  solved  the  wrong  problem.  Work hard to
improve.

[U-Boot-Users] Offset beginning of flash image?

[Marius Gröger]

> The problem is that PPCBoot doesn't support the rsh method of booting 
> kernels, so we are stuck w/ tftpboot. We can't use that for our vxworks 
> kernels.

You could try to boot your vxWorks kernels with any of the other
boot methods u-boot offers, e.g. tftp, bootp or dhcp.

If you _really_ want to run u-boot as second stage to the vxWorks loader,
I suggest you search the archives of this mailing list (and the old 
ppcboot's list, too) for tips on this issues. You already found TEXT_BASE,
you should also check CONFIG_MONITOR base and - depending on your platform
- you will need to disable the SDRAM initialisations. There are still
plenty of things likely to go astray if u-boot and vxWorks disagree on the
system setup (memory mapping being the most crucial), so you have to fully
understand what each one does. It is only worth the effort as a last 
resort, as getting everything straight can be time consuming. As usual,
you can always hire a more experienced consultant to do it for you.

Regards
Marius