[uml-devel] gdb debugging problem on uml-2.6.10

[uml-devel] gdb debugging problem on uml-2.6.10

[Mei,Jia]

Hi,

When I try gdb-5.3.90 with uml in vanilla-2.6.10 kernel. I found a problem.

When I set a breakpoint somewhere, and after some step, uml will
always get a SIGTRAP signal and trap into gdb.

Does anyone met the same problem as me? Any known fix for it?

thanks!

Eric


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Re: [uml-devel] gdb debugging problem on uml-2.6.10

[Jeff Dike]

On Thu, Apr 28, 2005 at 11:54:37PM +0800, Mei,Jia wrote:
> When I try gdb-5.3.90 with uml in vanilla-2.6.10 kernel. I found a problem.
> 
> When I set a breakpoint somewhere, and after some step, uml will
> always get a SIGTRAP signal and trap into gdb.

You are running UML inside gdb, not gdb inside UML, correct?

And you get a SIGTRAP from nowhere, someplace that you didn't set a 
breakpoint?

Can you post a gdb log of this?

And can you try something more recent than 2.6.10?

				Jeff


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Re: [uml-devel] gdb debugging problem on uml-2.6.10

[Blaisorblade]

On Thursday 28 April 2005 17:54, Mei,Jia wrote:
> Hi,
>
> When I try gdb-5.3.90 with uml in vanilla-2.6.10 kernel. I found a problem.
>
> When I set a breakpoint somewhere, and after some step, uml will
> always get a SIGTRAP signal and trap into gdb.
>
> Does anyone met the same problem as me? Any known fix for it?
No, I don't think there is any known fix for it. However, does this problem 
keep on and makes debugging impossible (i.e., after you "cont", does it keep 
stopping)?
> thanks!
>
> Eric
Hmm, are you doing debugging in SKAS or in TT mode? In the second case, then 
it can be a bug in the ptrace proxy (which has a big bug with some gdb 
releases >= 6.0).

In the first case, maybe it's something I observed too (I'm not sure because I 
don't use a lot gdb with UML)... Better, I've observed breakpoints being 
*skipped* by gdb.
-- 
Paolo Giarrusso, aka Blaisorblade
Skype user "PaoloGiarrusso"
Linux registered user n. 292729
http://www.user-mode-linux.org/~blaisorblade





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Re: [uml-devel] gdb debugging problem on uml-2.6.10

[Mei,Jia]

Blaisorblade wrote:
>>When I try gdb-5.3.90 with uml in vanilla-2.6.10 kernel. I found a problem.
>>
>>When I set a breakpoint somewhere, and after some step, uml will
>>always get a SIGTRAP signal and trap into gdb.
>>
>>Does anyone met the same problem as me? Any known fix for it?
> 
> No, I don't think there is any known fix for it. However, does this problem 
> keep on and makes debugging impossible (i.e., after you "cont", does it keep 
> stopping)?
> 
> Hmm, are you doing debugging in SKAS or in TT mode? In the second case, then 
> it can be a bug in the ptrace proxy (which has a big bug with some gdb 
> releases >= 6.0).
> 
> In the first case, maybe it's something I observed too (I'm not sure because I 
> don't use a lot gdb with UML)... Better, I've observed breakpoints being 
> *skipped* by gdb.

I'm sorry for the late response since away for a few days. It turn out 
to be the rootfs problem, although I don't know why (not related to 
tls), change to a new rootfs fixed it. Maybe don't need to chase more on 
this.
And appreciate you and Jeff's reply.

Eric


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Re: [uml-devel] gdb debugging problem on uml-2.6.10

[Blaisorblade]

On Thursday 05 May 2005 04:54, Mei,Jia wrote:
> Blaisorblade wrote:
> >>When I try gdb-5.3.90 with uml in vanilla-2.6.10 kernel. I found a
> >> problem.

> >>When I set a breakpoint somewhere, and after some step, uml will
> >>always get a SIGTRAP signal and trap into gdb.

> >>Does anyone met the same problem as me? Any known fix for it?

> > No, I don't think there is any known fix for it. However, does this
> > problem keep on and makes debugging impossible (i.e., after you "cont",
> > does it keep stopping)?

> > Hmm, are you doing debugging in SKAS or in TT mode? In the second case,
> > then it can be a bug in the ptrace proxy (which has a big bug with some
> > gdb releases >= 6.0).

> > In the first case, maybe it's something I observed too (I'm not sure
> > because I don't use a lot gdb with UML)... Better, I've observed
> > breakpoints being *skipped* by gdb.

> I'm sorry for the late response since away for a few days. It turn out
> to be the rootfs problem, although I don't know why (not related to
> tls), change to a new rootfs fixed it. Maybe don't need to chase more on
> this.
> And appreciate you and Jeff's reply.
This just happened to other three people (including me) in these days, so I'd 
like to know which rootfs's you used, to get a feeling of what could be going 
on. Thanks a lot.
-- 
Paolo Giarrusso, aka Blaisorblade
Skype user "PaoloGiarrusso"
Linux registered user n. 292729
http://www.user-mode-linux.org/~blaisorblade




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Re: [uml-devel] gdb debugging problem on uml-2.6.10

[Mei,Jia]

Blaisorblade wrote:
> This just happened to other three people (including me) in these days, so I'd 
> like to know which rootfs's you used, to get a feeling of what could be going 

The rootfs is a kind of minimal installation of FC3 (obtained from 
others), the new rootfs is also FC3 made by others and I was told 
there's nothing special trick for the new rootfs. I'll ask for more details.

Eric


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