Re: the "load" command and the .bss section

[Michael Snyder <msnyder@specifix.com>]

On Sun, 2008-04-27 at 05:09 -0400, Mike Frysinger wrote:
> i was doing a new board port using jtag and so was leveraging the "load" 
> command to setup the initial ELF in the relevant memory regions.  things kept 
> crashing on me and then i realized that the loading process wasnt actually 
> zeroing out the bss.  is there a reason for this ?  i googled and flipped 
> through the manual, but the details on what exactly the "load" command is 
> supposed to do is a bit on sketchy side.  from what i can tell from the gdb 
> source code and the actual output from running the command, it walks the 
> section headers (rather than the program headers ?) and loads up everything 
> that is in the file.  since the bss section doesnt actually exist in the file 
> and is only allocated, that is why it gets skipped ?
> 
> once i adapted my habits to first load the ELF and then manually zero the bss, 
> life was so much saner :).


In my understanding, it is not GDB's responsibility to zero the
.bss section.  That is the responsibility of the C Runtime.

Otherwise, how could the program run without gdb in the picture?

The gdb load command only addresses sections with the loadable
flag.  .bss is not loadable.