* domu_debug support removed on march 25th from traps.c in -unstable
@ 2005-04-13 5:39 Kip Macy
2005-04-13 5:47 ` softirq change was " Kip Macy
0 siblings, 1 reply; 6+ messages in thread
From: Kip Macy @ 2005-04-13 5:39 UTC (permalink / raw)
To: xen-devel, Keir Fraser
Why?
-Kip
^ permalink raw reply [flat|nested] 6+ messages in thread
* softirq change was Re: domu_debug support removed on march 25th from traps.c in -unstable
2005-04-13 5:39 domu_debug support removed on march 25th from traps.c in -unstable Kip Macy
@ 2005-04-13 5:47 ` Kip Macy
2005-04-13 17:44 ` Keir Fraser
0 siblings, 1 reply; 6+ messages in thread
From: Kip Macy @ 2005-04-13 5:47 UTC (permalink / raw)
To: xen-devel, Keir Fraser
The comments are pretty self-explanatory - but it looks like the trace
flag is no longer getting cleared on trap. Continue after
single-stepping no longer works. Any thoughts on why?
-Kip
On 4/12/05, Kip Macy <kip.macy@gmail.com> wrote:
> Why?
>
> -Kip
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: softirq change was Re: domu_debug support removed on march 25th from traps.c in -unstable
2005-04-13 5:47 ` softirq change was " Kip Macy
@ 2005-04-13 17:44 ` Keir Fraser
2005-04-13 17:48 ` Kip Macy
0 siblings, 1 reply; 6+ messages in thread
From: Keir Fraser @ 2005-04-13 17:44 UTC (permalink / raw)
To: Kip Macy; +Cc: xen-devel
The code belonged in debugger.h so I moved it there.
-- Keir
On 13 Apr 2005, at 06:47, Kip Macy wrote:
> The comments are pretty self-explanatory - but it looks like the trace
> flag is no longer getting cleared on trap. Continue after
> single-stepping no longer works. Any thoughts on why?
>
> -Kip
>
>
>
> On 4/12/05, Kip Macy <kip.macy@gmail.com> wrote:
>> Why?
>>
>> -Kip
>>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: softirq change was Re: domu_debug support removed on march 25th from traps.c in -unstable
2005-04-13 17:44 ` Keir Fraser
@ 2005-04-13 17:48 ` Kip Macy
2005-04-13 17:59 ` Keir Fraser
0 siblings, 1 reply; 6+ messages in thread
From: Kip Macy @ 2005-04-13 17:48 UTC (permalink / raw)
To: Keir Fraser; +Cc: xen-devel
No idea why the trace trap flag isn't getting cleared? I can work at
around it at the application level but that is aesthetically
displeasing.
-Kip
On 4/13/05, Keir Fraser <Keir.Fraser@cl.cam.ac.uk> wrote:
> The code belonged in debugger.h so I moved it there.
>
> -- Keir
>
>
> On 13 Apr 2005, at 06:47, Kip Macy wrote:
>
> > The comments are pretty self-explanatory - but it looks like the trace
> > flag is no longer getting cleared on trap. Continue after
> > single-stepping no longer works. Any thoughts on why?
> >
> > -Kip
> >
> >
> >
> > On 4/12/05, Kip Macy <kip.macy@gmail.com> wrote:
> >> Why?
> >>
> >> -Kip
> >>
>
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: softirq change was Re: domu_debug support removed on march 25th from traps.c in -unstable
2005-04-13 17:48 ` Kip Macy
@ 2005-04-13 17:59 ` Keir Fraser
2005-04-13 18:05 ` Kip Macy
0 siblings, 1 reply; 6+ messages in thread
From: Keir Fraser @ 2005-04-13 17:59 UTC (permalink / raw)
To: Kip Macy; +Cc: xen-devel
On 13 Apr 2005, at 18:48, Kip Macy wrote:
> No idea why the trace trap flag isn't getting cleared? I can work at
> around it at the application level but that is aesthetically
> displeasing.
You mean that the TF bit is not cleared by the domu_debug code when it
should be? The correct place to fix this is in
include/asm-x86/debugger.h in debugger_trap_entry().
In general (not using domu_debug) it is not Xen's job to clear TF. We
clear it when we 'bounce' the exception into the guest OS, but the
saved application stack frame will include EFLAGS with the TF bit still
set. This matches real hardware.
-- Keir
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: softirq change was Re: domu_debug support removed on march 25th from traps.c in -unstable
2005-04-13 17:59 ` Keir Fraser
@ 2005-04-13 18:05 ` Kip Macy
0 siblings, 0 replies; 6+ messages in thread
From: Kip Macy @ 2005-04-13 18:05 UTC (permalink / raw)
To: Keir Fraser; +Cc: xen-devel
> You mean that the TF bit is not cleared by the domu_debug code when it
> should be? The correct place to fix this is in
> include/asm-x86/debugger.h in debugger_trap_entry().
Yes. Continuing after single-stepping no longer works.
> In general (not using domu_debug) it is not Xen's job to clear TF. We
> clear it when we 'bounce' the exception into the guest OS, but the
> saved application stack frame will include EFLAGS with the TF bit still
> set. This matches real hardware.
No it isn't Xen's job to clear it under normal circumstances as that
would break PTRACE_SINGLESTEP in user-space. However, it was what the
PDB code was doing and it seemed easy enough to clear it there to
emulate PTRACE_SINGLESTEP for the kernel.
I honestly don't care where it happens, it is easy enough to clear the
TF from xc_ptrace.c. I just happened to be *extremely* tired last
night and was dealing with other issues, so I was frustrated when that
didn't work. I'll just incorporate my fix to xc_ptrace.c in with the
FreeBSD fixes for -unstable.
-Kip
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2005-04-13 18:05 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2005-04-13 5:39 domu_debug support removed on march 25th from traps.c in -unstable Kip Macy
2005-04-13 5:47 ` softirq change was " Kip Macy
2005-04-13 17:44 ` Keir Fraser
2005-04-13 17:48 ` Kip Macy
2005-04-13 17:59 ` Keir Fraser
2005-04-13 18:05 ` Kip Macy
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