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Re: the "load" command and the .bss section
- From: Michael Snyder <msnyder at specifix dot com>
- To: Mike Frysinger <vapier at gentoo dot org>
- Cc: gdb at sourceware dot org
- Date: Mon, 28 Apr 2008 11:21:54 -0700
- Subject: Re: the "load" command and the .bss section
- References: <email@example.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.