Re: [Ksummit-2008-discuss] DTrace

[Sam Ravnborg <sam@ravnborg.org>]

On Tue, Jul 01, 2008 at 08:12:43AM -0400, Theodore Tso wrote:
> On Tue, Jul 01, 2008 at 01:05:17PM +0200, Sam Ravnborg wrote:
> > On Tue, Jul 01, 2008 at 06:15:07AM -0400, Theodore Tso wrote:
> > > 
> > > I've pulled apart RHEL's rpm macro magic before, and it's not a
> > > pleasant wading through all of the files; maybe we can teach the
> > > native kernel build infrastructure how to create debuginfo files so
> > > that each distribution doesn't have to re-invent the wheel from
> > > scratch, but rather can reuse common infrastructure in Kbuild....
> > 
> > What is needed to create debuginfo files?
> > Seems like a simple thing to integrate in kbuild
> > if this is per file or per module.
> 
> Well, the simple/stupdiest thing we can do is simply have an alternate
> target which installs the modules in
> 
>        $(INSTALL_MOD_PATH)/usr/lib/debug/$(KERNELRELEASE)
> 
> ... while ignoring the INSTALL_MOD_STRIP option.  You may recall that
> that I submitted the patch to add INSTALL_MOD_STRIP (commit
> ac031f26e); this was from an earlier attempt of mine to use
> kdump/systemtap.
> 
> RHEL's rpm macro magic does some additional objcopy's which I'll have
> to try to ease out to strip out the text segments and only leave the
> debug information in debuginfo files, which helps slim them down a
> little.  
> 
> > 
> > If it is for the kernel as a whole things gets a bit more complex.
> > 
> 
> It would be nice to do this for the base kernel as well (a vmlinux
> with strip --strip-debug applied takes only 6 megs in /boot on my
> system, but a vmlinux with full debugging information takes 66 megs;
> so moving the unstripped vmlinux out of /boot to /usr/lib/debug would
> be quite helpful for people who created their /boot partition not
> allowing for the rather dramatic increase in size needed for kernels
> built with debugging information.)

It all seems quite simple to do with a bit of careful testing.
I can give it a try when I'm properly installed in my new house.
So lets hope someone jump in and do it.

	Sam