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Re: [microblaze-uclinux] microblaze-uclinux-elf2flt mistranslation

Hi Steve,
I ran into the same problem a year or so ago. I posted this issue to the group in June of 2008: 
http://www.itee.uq.edu.au/~listarch/microblaze-uclinux/archive/2008/06/msg00108.html
I came to the same conclusions that you did. Instead of spending a lot of time trying to fix elf2flt, I developed a work-around:
* Take the same elf file that was used by elf2flt to generate the flat executable and create a binary file with mb-objcopy. * Replace the .data section of the flat executable with the binary file's version. I created a utility to do compare the 2 data sections and do the replacement. I often see a couple mismatches between the binary file's data section and the flat file's. I have this as part of every microblaze compile. 

Here is a run of tail end of my compile script:
mb-flthdr -p la5600
la5600
   Magic:        bFLT
   Rev:          4
   Build Date:   Tue May 26 18:07:37 2009
   Entry:        0x50
   Data Start:   0x2eb40
   Data End:     0x41ec0
   BSS End:      0x55dc0
   Stack Size:   0x8000
   Reloc Start:  0x41ec0
   Reloc Count:  0x12e7
   Flags:        0x1 ( Load-to-Ram )
==============================================================
* Compare flat file Data Sect with bin file & fix flat file  *
==============================================================
mb-objcopy -O binary la5600.gdb la5600.bin
./la_fltfix -v -f la5600 -b la5600.bin -o la5600
./la_fltfix INFO: Flat File Flags=0x00000001
./la_fltfix INFO: DataSect Len=0x13380,78720 Ofst:Flt=0x2eb40 Bin=0x2eb00
./la_fltfix INFO: DIFF @DataSect+0xf29e Flt=0xec Bin=0xed
./la_fltfix INFO: DIFF @DataSect+0xf29f Flt=0x6c Bin=0xd8
./la_fltfix INFO: DIFF @DataSect+0xf31e Flt=0xec Bin=0xed
./la_fltfix INFO: DIFF @DataSect+0xf31f Flt=0x6c Bin=0xd8
./la_fltfix INFO: 4 DIFFs found
./la_fltfix INFO: Created Output flat file "la5600"
./la_fltfix INFO: Return code=0

I hope this helps.

Rod Campbell

Steven J. Magnani wrote:

Hi,

Has anyone run into problems with microblaze-uclinux-elf2flt?

We have a program that contains a constant global array something like
this:

const struct
{
   const char*          source;
   const char*          target;
   unsigned long        flags;
   const char*          options;
   unsigned int         channel;
   unsigned long        devnum;
} myGlobalStruct[9] = { blah blah blah };

What we are seeing is for certain sequences of executable code, one of
the .target fields in the array gets mis-translated, so instead of
pointing to the constant string associated with array element [3], it
points to the constant string associated with array element [0]. It's
definitely a translation problem because I can use
microblaze-uclinux-objcopy to extract the .data segment from the .gdb
file and the structure is correct there.

Depending on how we change the program flow, the problem can come and
go. If we add a printf to one module the problem goes away.

Any suggestions? Is there a more recent version of microblaze-uclinux
tools available anywhere, or in the works? Tool problems like this make
us very nervous because there's no telling what else is being corrupted.

Thanks.
------------------------------------------------------------------------
 Steven J. Magnani               "I claim this network for MARS!
 www.digidescorp.com              Earthling, return my space modulator!"

 #include <standard.disclaimer>


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--
Rod Campbell
Senior Software Engineer
Linear Acoustic, Inc.

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