amd64 kernel modules: mapping sections to addresses

[Navdeep Parhar]

On Tue, Jun 22, 2010 at 12:34:49AM +0300, Andriy Gapon wrote:
> on 21/06/2010 23:44 Navdeep Parhar said the following:
> > On Mon, Jun 21, 2010 at 04:10:45PM -0400, John Baldwin wrote:
> >> On Monday 21 June 2010 11:57:17 am Andriy Gapon wrote:
> >>> on 21/06/2010 18:43 John Baldwin said the following:
> >>>> np@ has a patch to gdb to fix this for kgdb.  I haven't committed it as it 
> >>>> patched gdb internals and wasn't in a kgdb-specific place, but I'm not 
> >> sure of 
> >>>> a better way to fix kgdb.
> >>> Oh, yes, section mapping is done in common gdb code.
> >>> Perhaps kld.c shouldn't call build_section_table, but directly call
> >>> bfd_map_over_sections with a custom variant of add_to_section_table?
> >>> Can you please share the patch?
> >> It was deeper level than that, I'd have to dig it up.
> > 
> > I'm using this patch these days:
> > http://people.freebsd.org/~np/kgdb+kld+amd64.diff
> > 
> > The changes to the kernel linker were not required originally.  See this
> > for why they had to be made:
> > http://lists.freebsd.org/pipermail/freebsd-hackers/2009-November/030093.html
> > 
> > The patch is quite crude and I have no idea how it behaves on other
> > platforms.
> 
> Thanks a lot!  These are exact issues that I hit and the patches are what I
> think they should be, take or give.  I don't think they are really crude.
> I will try to get them committed.
> 
> Kernel linker change is good as is, I'd just like to move the zero size check
> before the switch statement.

I'm not so sure about this.  There is code inside the second switch that runs
whether sh_size is 0 or not.  Either all of it is pointless code (when sh_size
is 0) or or you'll make sure that it still runs, right?

Regards,
Navdeep

> 
> gdb change - I'd rather do it via kld_current_sos,
> kld_relocate_section_addresses.  I'd like to avoid changing common gdb code for
> a variety of reasons.
> 
> -- 
> Andriy Gapon