[U-Boot-Users] code relocation and symbolic debugging
wd at denx.de
Tue Mar 20 02:42:07 CET 2007
In message <f608b67d0703191805t6379c48an24ea9d9d41277d11 at mail.gmail.com> you wrote:
> a pain, especially when trying symbolic debugging. I of course know
> about the gdb add-symbol-file command, but I couldn't figure out how
> to make it relocate symbols along with the text segment. As a result,
Then you obviously did not read the manual. Please RTFM.
> I can set breakpoints and examine automatic variables, but can't see
> static/global variables using the gdb. How do others handle this
> situation - any hits will be highly appreciated.
We just do as described in the manual.
> Now, I don't want to sound too much off the mark, but why is this
> trick even needed? For at least 10 years now gnu tools provide the
> ability to generate bin images of the executable files and to
> concatenate otherwise noncontiguous segments in one file.
If you want to be able to erase / progarm the flash, at least youyr
flash driver must be running from non-flash memory (at leats on most
standard flash chips). If you want to be able to update U-Boot in
flash you must have all of U-Boot running in some other memory.
This requires to copy & relocate the image.
And this has nothing to do with where the code/data segments are
> Utilizing this feature would allow to benefit from all the u-boot
> early startup elegant smarts (running with data in the cache, testing
> the entire dram, stc)., then the first stage code would just move the
> main chunk to the predefined location and pass control to it. This way
> no need to worry about adjusting tabled addresses, about data not
> fitting into the room allotted, about gdb not alllowing to see
> variables - this approach is pretty much worry free at least on mips
> and ppc architectures where I extensively deployed it before joining
> the u-boot club.
Feel free to submit patches - if they actually work we will be happy
to consider them.
I'm just afraid that you miss a few points...
> Of course with such a heavy legacy like u-boot has it is difficult to
> switch on a whim, but would this be even considered? And why has not
> it been done like that in the first place?
Because nobody was clever enough to implement it? Or maybe because it
does not work? Dunno...
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