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Date:      Tue, 8 Apr 2014 21:17:53 -0600
From:      Warner Losh <imp@bsdimp.com>
To:        Ian Lepore <ian@FreeBSD.org>
Cc:        Steve Kargl <sgk@troutmask.apl.washington.edu>, freebsd-arch <freebsd-arch@FreeBSD.org>
Subject:   Re: Time for turning off gdb by default? Or worse...
Message-ID:  <A2053A11-FDFD-4D72-A15B-8E5378E6BF7F@bsdimp.com>
In-Reply-To: <1396995427.81853.449.camel@revolution.hippie.lan>
References:  <DD38131E-9A43-4EFA-A27D-ED6B64F6A35A@bsdimp.com> <20140408212435.GA75404@troutmask.apl.washington.edu> <57ECB078-3D7A-4BE8-AA29-1ED7BB347DBD@bsdimp.com> <1396995427.81853.449.camel@revolution.hippie.lan>

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On Apr 8, 2014, at 4:17 PM, Ian Lepore <ian@FreeBSD.org> wrote:

> On Tue, 2014-04-08 at 15:43 -0600, Warner Losh wrote:
>> On Apr 8, 2014, at 3:24 PM, Steve Kargl =
<sgk@troutmask.apl.washington.edu> wrote:
>>=20
>>> On Tue, Apr 08, 2014 at 02:34:35PM -0600, Warner Losh wrote:
>>>=20
>>> (courtesy line wrap to something well below 80 characters)
>>>=20
>>>> The gdb in the tree seems to be of very limited usefulness
>>>> these days. It doesn?t seem to work on clang-enabled
>>>> architectures w/o building -gdwarf-2, it doesn?t seem to work
>>>> with threaded applications, and on some architectures it
>>>> doesn?t seem to work at all (mips comes to mind, but it may
>>>> have been the two binaries I tried).
>>>>=20
>>>=20
>>> (patch removed)
>>>=20
>>>> to the tree, which will turn gdb off by default.  It may make
>>>> more sense to just remove it entirely, but I?m not sure I want
>>>> to go there just yet in case there are things that I?m missing.
>>>> I believe that the port will be adequate for all architectures
>>>> we support, but haven?t tested this directly yet. I do know
>>>> that on amd64, the port just worked, where the in-tree gdb
>>>> was an epic fail.
>>>=20
>>> I suppose the obvious questions are:
>>>=20
>>> 1) Is lldb ready for prime time?
>>=20
>> Doesn=A2t matter.
>>=20
>>> 2) What effect does this have on kgdb?  Note, /sys/conf/NOTES =
contains
>>=20
>> Unfortunately, kgdb isn=A2t available as a port, so that does matter. =
It is one thing arguing against this change.
>>=20
>>> #makeoptions	DEBUG=3D-g		#Build kernel with =
gdb(1) debug symbols
>>>=20
>>> Should this be updates to DEBUG=3D-gdwarf-2?
>>=20
>> Nope. It should stay exactly as it is. We convert -g to -gdwarf-2 for =
those compilers that need it.
>=20
> Only when building the kernel.  For userland we've got nothing.  gdb
> aside, even addr2line doesn't work on userland binaries anymore.  It
> used to be hard to do debugging for arm.  Now it's impossible.

I thought I=A2ve had it work when I used DEBUG_FLAGS=3D-gdwarf-2 rather =
than DEBUG_FLAGS=3D-g.

Warner=



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