Re: 6.0R GENERIC makeoptions DEBUG=-g

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Re: 6.0R GENERIC makeoptions DEBUG=-g

Simon Ironside
Hi,

/sys/i386/conf/GENERIC has this line uncommented - is this on purpose? I
commented it out before building a new kernel.

makeoptions     DEBUG=-g

Cheers,
Simon

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Re: 6.0R GENERIC makeoptions DEBUG=-g

Xin LI-5
Hi, Simon,

On 11/14/05, Simon Ironside <[hidden email]> wrote:
> Hi,
>
> /sys/i386/conf/GENERIC has this line uncommented - is this on purpose? I
> commented it out before building a new kernel.
>
> makeoptions     DEBUG=-g

I think this is intentional.  Having DEBUG=-g means that you have a
kernel.debug which contains debugging symbols, which is quite useful
if you get a kernel panic and want to report it back.  On the other
hand, debugging symbols would be stripped before you install a new
kernel so it does not affect the running kernel.

Cheers,
--
Xin LI <[hidden email]> http://www.delphij.net

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Re: 6.0R GENERIC makeoptions DEBUG=-g

Simon Ironside
Hello,

> I think this is intentional.  Having DEBUG=-g means that you have a
> kernel.debug which contains debugging symbols, which is quite useful
> if you get a kernel panic and want to report it back.  On the other
> hand, debugging symbols would be stripped before you install a new
> kernel so it does not affect the running kernel.

This has changed since 5.4 - I just wondered why and whether I would be
best leaving it as is or commenting it out.

Simon
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Re: 6.0R GENERIC makeoptions DEBUG=-g

Xin LI-5
On 11/14/05, Simon Ironside <[hidden email]> wrote:
[snip]
> This has changed since 5.4 - I just wondered why and whether I would be
> best leaving it as is or commenting it out.

My personal suggestion would be that you keep it as-is, since it saves
your time when you have kernel panics and wants someone to quickly
address the bug without having to crash your system for a second time
to get the backtrace =-)

Cheers,
--
Xin LI <[hidden email]> http://www.delphij.net

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Re: 6.0R GENERIC makeoptions DEBUG=-g

Dev Tugnait
In reply to this post by Simon Ironside
safe to leave un-commented no hindrance in performance.

On Mon, 2005-11-14 at 08:53 +0000, Simon Ironside wrote:

> Hello,
>
> > I think this is intentional.  Having DEBUG=-g means that you have a
> > kernel.debug which contains debugging symbols, which is quite useful
> > if you get a kernel panic and want to report it back.  On the other
> > hand, debugging symbols would be stripped before you install a new
> > kernel so it does not affect the running kernel.
>
> This has changed since 5.4 - I just wondered why and whether I would be
> best leaving it as is or commenting it out.
>
> Simon
> _______________________________________________
> [hidden email] mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-questions
> To unsubscribe, send any mail to "[hidden email]"

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Re: 6.0R GENERIC makeoptions DEBUG=-g

Robert N. M. Watson-2
In reply to this post by Simon Ironside

On Mon, 14 Nov 2005, Simon Ironside wrote:

> /sys/i386/conf/GENERIC has this line uncommented - is this on purpose? I
> commented it out before building a new kernel.
>
> makeoptions DEBUG=-g

This was by accident, but actually isn't a bad idea.  We discovered the
problem at the last minute, after the 6.0-R builds had completed, and as
they were rsyncing to mirrors.  After thinking about it for a few minutes,
we decided that actually, it has some nice benefits that made it worth not
rebuilding and re-mirroring.  If we were earlier in the release cycle, we
might have changed the setting, however.

We identified a few specific upsides and downsides:

Good: We now have debugging symbols easily available and widely accessible
for the GENERIC kernel shipped with the release.  This makes it much
easier for developers to debug problems using that kernel, as we no longer
need to ask end-users to build a kernel with debugging symbols, etc, in
order to debug a problem.  Especially for a .0 release, this is a very
useful, and has presented a problem in previous releases.

Bad: Kernel build times are now significantly slower, and required space
to build a kernel significantly larger by default.

We'll see how it settles out -- CPUs are a lot larger, and disks a lot
bigger than they used to be.  The kernel is stripped of debugging symbols
before it is installed, so this is only potentially a problem on systems
that already have enough space to hold source, builds, etc, and doesn't
affect systems where the kernel is installed but not built.  I.e., this
doesn't affect the footprint for embedded systems, or systems where a
kernel is built centrally and then distributed.

My recommendation would be to leave -g in unless you know that the added
build time and disk space for the build process will be a problem for you.
Hopefully you don't ever run into any problems requiring debug symbols,
but if you do it will probably save you some time and hassle, especially
if it's a problem that occurs once every six months, in which case
rebooting with a kernel with known symbol layout will mean waiting six
months to debug the problem. :-)

Robert N M Watson
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