[Crash-utility] Why module's global symbol cannot be displayed in crash? [ARM]

[Dave Anderson]

----- Original Message -----
> On Tue, Mar 19, 2013 at 10:58 PM, Dave Anderson <anderson at redhat.com>
> wrote:
> >
> >
> > ----- Original Message -----
> >> Dave,
> >>
> >> On Tue, Mar 19, 2013 at 10:31 PM, Dave Anderson
> >> <anderson at redhat.com>
> >> wrote:
> >> >
> >> >
> >> > ----- Original Message -----
> >> >> Hi list,
> >> >>
> >> >> I find in current 6.1.4 crash, when load module with "mod -S",
> >> >> only module's function symbol could be parsed out.
> >> >>
> >> >> But for module's global variant, crash cannot find related
> >> >> symbol...
> >> >> Any idea for this?
> >> >>
> >> >
> >> > Without the debuginfo data from the module.ko.debug file, crash
> >> > gets all of its module symbol data from the kernel.  So it uses
> >> > what's available in the in-kernel /proc/kallsyms list plus the
> >> > information stored in each module's "struct module".  The
> >> > store_module_symbols_v2() function does the work.
> >> >
> >> > If "mod -[sS]" is used, then crash has access to full debuginfo
> >> > data
> >> > from the module.ko.debug file.  In that case, the
> >> > store_load_module_symbols()
> >> > function does the work.
> >> >
> >>
> >> For current, what I saw is when I have loaded the module, only
> >> the t or T type symbol is installed, while others like d or D type it
> >> would not be loaded at all...
> >>
> >> While for one symbol, I already knows its member has a specific
> >> magic number, so that I search the memory, and find its virtual
> >> address becomes to 0xexxxxxxx, not the 0xbfxxxxxx.
> >> So does it mean the debuginfo in that module only has text related,
> >> while data type are all muted, and why?...
> >>
> >>
> >> Thanks,
> >> Lei
> >
> > I have no idea.  With x86/x86_64 you can see text, data and bss
> > symbols both before and after the "mod -[sS]" command is run.
> >
> > Dave
> >
> 
> Add Mike...
> 
> Mike,
> Do you have any idea for this?
> 
> Thanks,
> Lei

On that note, I only have a handful of sample ARM vmcore dumpfiles,
and none of their kernels have any modules.  My supposition was that
it is simply common usage that ARM kernels are built without modules
because of their typically embedded use-cases.

In any case, if somebody can make a sample ARM vmcore available to
me that does have modules, I'd appreciate having it on hand for testing.

Thanks,
  Dave