Date: Tue, 05 Apr 2011 15:49:01 -0700 From: Julian Elischer <julian@freebsd.org> To: Navdeep Parhar <nparhar@gmail.com> Cc: Justin Hibbits <chmeeedalf@gmail.com>, FreeBSD Current <current@freebsd.org> Subject: Re: KGDB stack traces in the kernel. Message-ID: <4D9B9C5D.4000909@freebsd.org> In-Reply-To: <BANLkTinPdVUac6YGwf4GvOE7gtndbQERaQ@mail.gmail.com> References: <4D9A4CE5.5090900@freebsd.org> <ACA0C058-28F4-4A0E-B9EC-E26E35219449@gmail.com> <4D9B7C92.6030901@freebsd.org> <BANLkTinPdVUac6YGwf4GvOE7gtndbQERaQ@mail.gmail.com>
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On 4/5/11 1:35 PM, Navdeep Parhar wrote:
> On Tue, Apr 5, 2011 at 1:33 PM, Julian Elischer<julian@freebsd.org> wrote:
>> On 4/4/11 6:04 PM, Justin Hibbits wrote:
>>> On Apr 4, 2011, at 6:57 PM, Julian Elischer wrote:
>>>> is there anyone here with enough gdb/kgdb source experience to know what
>>>> we would need to put on the stack at fork_exit() to make it stop when it
>>>> gets there?
>>>>
>>>> not only is it annoying but it slows down debugging because kgdb and the
>>>> ddd
>>>> front end ask for stacks a LOT. sometimes it actually just hangs as the
>>>> stack
>>>> goes into a loop and never ends.
>>>>
>>>> I had a quick look but didn't spot how gdb decides it has reached the end
>>>> of a stack.
>>>>
>>>> Julian
>>> From my experience, it checks for a NULL stack chain pointer. Once that
>>> reaches NULL, it's the end of the stack.
>>>
>>> - Justin
>>>
>> I'll try adding NULL when we build the intial stack up.
>> :-)
> What does ddb do? It always seems to get this stuff correct.
>
> Navdeep
it has all sorts of special code that knows the intricacies of
freebsd's stack.
(k)gdb only knows more generic stuff.
hmmm set 0 into the saved ebp bit that didn't help.. I'll play a bit more
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