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

[Mike Frysinger <vapier at gentoo dot org>]

On Sunday 27 April 2008, Daniel Jacobowitz wrote:
> On Sun, Apr 27, 2008 at 05:09:31AM -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 ?
>
> Load puts things at their LMA rather than their VMA.  So it assumes
> that whatever sets up load -> virtual also handles bss; it's more like
> flash programming than like the Linux kernel's loader.  Heck,
> sometimes it is flash programming...
>
> IIRC we have a couple of old requests for a version of load which
> drops things at their VMA.  That one would have to clear the BSS.

what would be the way to extend things ?  getopt-style flags to load ?  a new 
command ?  i may take a look (according to my wants/needs), but i'm not 
terribly good with gdb code base, so i wont promise anything ...
-mike

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