[U-Boot-Users] problem when running the bootm command

[U-Boot-Users] problem when running the bootm command

[Erez Koelewyn]

Hi,

I am using the M5282EVB configuration. I have come across the
following problem: I load a compressed linux image into address 400000
(I leave enough
 room for it to be decompressed at address 100000).
 I then run -> bootm 400000
 This works fine (the image is decompressed at address 100000 and runs
correctly).

 Now I reset the board, download the compressed image again (using
 iminfo to very it's header is there and correct) and again I run ->
 bootm 400000

 This time I get an exception (this happens consistently until I
 program U-Boot again into FLASH, at which time I can again use bootm
 successfully only once):

 -> bootm 400000
 ## Booting image at 00400000 ...
   Image Name:
   Image Type:   M68K Linux Standalone Program (gzip compressed)
   Data Size:    1249874 Bytes =  1.2 MB
   Load Address: 00100000
   Entry Point:  00100000
   Verifying Checksum ... OK
   Uncompressing Standalone Application ...

 *** Unexpected exception ***
 Vector Number: 3  Format: 04  Fault Status: 4

 PC: 00fe5d48    SR: 00002704    SP: 00f9155c
 D0: 00000000    D1: 00000000    D2: 00000000    D3: 0000011a
 D4: 00000000    D5: 00000000    D6: 004000d8    D7: 00fa1f90
 A0: 00000009    A1: 00fac8e0    A2: 00fa28e0    A3: 00f91afe
 A4: 00fa2928    A5: 00ff7600    A6: 00f91ad4

 *** Please Reset Board! ***

The problem cannot e related to overwriting critical areas in RAM
because I don't overwrite U-Boot's region or the region where I store
the packaged image.

Did anyone come across this problem

 Thanks,

 Erez

[U-Boot-Users] problem when running the bootm command

[Jerry Van Baren]

Erez Koelewyn wrote:
> Hi,
> 
> I am using the M5282EVB configuration. I have come across the
> following problem: I load a compressed linux image into address 400000
> (I leave enough
>  room for it to be decompressed at address 100000).
>  I then run -> bootm 400000
>  This works fine (the image is decompressed at address 100000 and runs
> correctly).
> 
>  Now I reset the board, download the compressed image again (using
>  iminfo to very it's header is there and correct) and again I run ->
>  bootm 400000
> 
>  This time I get an exception (this happens consistently until I
>  program U-Boot again into FLASH, at which time I can again use bootm
>  successfully only once):
> 
>  -> bootm 400000
>  ## Booting image at 00400000 ...
>    Image Name:
>    Image Type:   M68K Linux Standalone Program (gzip compressed)
>    Data Size:    1249874 Bytes =  1.2 MB
>    Load Address: 00100000
>    Entry Point:  00100000
>    Verifying Checksum ... OK
>    Uncompressing Standalone Application ...
> 
>  *** Unexpected exception ***
>  Vector Number: 3  Format: 04  Fault Status: 4
> 
>  PC: 00fe5d48    SR: 00002704    SP: 00f9155c
>  D0: 00000000    D1: 00000000    D2: 00000000    D3: 0000011a
>  D4: 00000000    D5: 00000000    D6: 004000d8    D7: 00fa1f90
>  A0: 00000009    A1: 00fac8e0    A2: 00fa28e0    A3: 00f91afe
>  A4: 00fa2928    A5: 00ff7600    A6: 00f91ad4
> 
>  *** Please Reset Board! ***
> 
> The problem cannot e related to overwriting critical areas in RAM
> because I don't overwrite U-Boot's region or the region where I store
> the packaged image.
> 
> Did anyone come across this problem
> 
>  Thanks,
>  Erez

I'm clueless but that never stopped me from guessing.  ;-)

It sounds like your linux image is scribbling in flash, messing up 
u-boot (but not fatally).  Do you have a flash file system configured in 
your linux image?  Any other reason your linux image would overwrite 
flash?  If you dump the end portion of the *flash* u-boot image before 
and after the successful linux boot, does it show corruption?

If that isn't the problem the follow up question is: what is the 
unexpected exception vector number 3, what is the meaning of the PC 
(where the exception occurred), what does the stack tell you when you 
dump it?

Good luck,
gvb

[U-Boot-Users] problem when running the bootm command

[Erez Koelewyn]

On 10/23/07, Jerry Van Baren <gerald.vanbaren@ge.com> wrote:
> It sounds like your linux image is scribbling in flash, messing up
> u-boot (but not fatally).  Do you have a flash file system configured in
> your linux image?  Any other reason your linux image would overwrite
> flash?  If you dump the end portion of the *flash* u-boot image before
> and after the successful linux boot, does it show corruption?

I never thoughtLinux might be corrupting FLASH memory for the following reasons:

1. When I load and run linux as a .bin file there is never any
problem. Ah! yes, another good test would be to run load and run a
linux .bin file (on a freshly programmed board) and after that try to
inflate a packaged linux image.
2. Flash memory sectors where U-Boot resides are protected (read
only). Could linux be removing the protection? I should check.
3. The problem occurs even when uncompressing from a RAM location to
another RAM location, before linux has a chance to run. But obviously
the corruption could still happen in the first run as you pointed out.

I will do as you suggest and compare the FLASH memory dump with my
U-Boot image, it's a very good idea.

> If that isn't the problem the follow up question is: what is the
> unexpected exception vector number 3, what is the meaning of the PC
> (where the exception occurred), what does the stack tell you when you
> dump it?

Yes, that's the hard part. I was hoping to aviod the hassle in case
someone already encountered this problem and provided a patch (I
couldn't find anything in previous postings though).

Thank you for your advice,

Erez

[U-Boot-Users] problem when running the bootm command

[Erez Koelewyn]

An update on this:

It seems to be related to saving the environment variables in FLASH.
Only after I save the environment variables to FLASH does the problem
happen. Something there is overwriting U-Boot's code. This is also why
the first time after programming the board it works OK, since the
U-Boot's code runs from RAM, only after restarting the board do we
load the corrupted code.

I'm looking into it. Thank you for all your help