* GDB without traditional frames
@ 2003-09-25 2:02 Andrew Cagney
2003-09-25 14:45 ` Andrew Cagney
2003-09-26 21:36 ` y2bismil
0 siblings, 2 replies; 4+ messages in thread
From: Andrew Cagney @ 2003-09-25 2:02 UTC (permalink / raw)
To: gdb
Hello,
As an accademic exercise I decided to see what would happen if a PPC64
GDB was configured to only use dwarf2 cfi (just disable the trad-frame
code).
The short answer is "it works (mostly)".
The long answer is ...
It relies on there being 100% coverage of the CFI. System libraries can
sometimes be lacking. Assembler stubs, for instance, will trip things
up. Irony here is that it's those same assembler routines that trip up
traditional unwinders. Anyway, an unwinder capable of unwinding just LR
works pretty well.
GCC CFI leaves registers as "unspecified" and the "assume same value"
hack isn't sufficient. For PPC64, GCC points the "return_column" at
dwarf2 num 65 (that's the FPSCR but lets ignore that m'key :-). It
needs to specify that by default the "return_column" has the same value
as the "LR" column.
So while trad unwind code is useful, I think it can now be considered
largely optional.
I've got more GCC bugs to file :-)
enjoy,
Andrew
^ permalink raw reply [flat|nested] 4+ messages in thread
* GDB without traditional frames
2003-09-25 2:02 GDB without traditional frames Andrew Cagney
@ 2003-09-25 14:45 ` Andrew Cagney
2003-09-26 21:36 ` y2bismil
1 sibling, 0 replies; 4+ messages in thread
From: Andrew Cagney @ 2003-09-25 14:45 UTC (permalink / raw)
To: gdb
Hello,
As an accademic exercise I decided to see what would happen if a PPC64
GDB was configured to only use dwarf2 cfi (just disable the trad-frame
code).
The short answer is "it works (mostly)".
The long answer is ...
It relies on there being 100% coverage of the CFI. System libraries can
sometimes be lacking. Assembler stubs, for instance, will trip things
up. Irony here is that it's those same assembler routines that trip up
traditional unwinders. Anyway, an unwinder capable of unwinding just LR
works pretty well.
GCC CFI leaves registers as "unspecified" and the "assume same value"
hack isn't sufficient. For PPC64, GCC points the "return_column" at
dwarf2 num 65 (that's the FPSCR but lets ignore that m'key :-). It
needs to specify that by default the "return_column" has the same value
as the "LR" column.
So while trad unwind code is useful, I think it can now be considered
largely optional.
I've got more GCC bugs to file :-)
enjoy,
Andrew
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: GDB without traditional frames
2003-09-25 2:02 GDB without traditional frames Andrew Cagney
2003-09-25 14:45 ` Andrew Cagney
@ 2003-09-26 21:36 ` y2bismil
2003-09-26 21:54 ` Daniel Berlin
1 sibling, 1 reply; 4+ messages in thread
From: y2bismil @ 2003-09-26 21:36 UTC (permalink / raw)
To: gdb
Hey all,
not sure if you remember, but I was trying to get a binary compiled on
Openwatcom 1.0 to be debugged using GDB. Anyways, from what I can gather,
Watcom used a draft standard for their DWARF format
Unix International Programming Languages SIG, Version 2, Draft 6, dated April
12, 1993
Just to see if its a quick fix that could be made, I was wondering if anyone
knows the exact document GDB's DWARF abilities are based on.
Thanks all,
Yamin
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: GDB without traditional frames
2003-09-26 21:36 ` y2bismil
@ 2003-09-26 21:54 ` Daniel Berlin
0 siblings, 0 replies; 4+ messages in thread
From: Daniel Berlin @ 2003-09-26 21:54 UTC (permalink / raw)
To: y2bismil; +Cc: gdb
On Sep 26, 2003, at 5:19 PM, y2bismil@engmail.uwaterloo.ca wrote:
> Hey all,
>
> not sure if you remember, but I was trying to get a binary compiled on
> Openwatcom 1.0 to be debugged using GDB. Anyways, from what I can
> gather,
>
> Watcom used a draft standard for their DWARF format
> Unix International Programming Languages SIG, Version 2, Draft 6,
> dated April
> 12, 1993
>
First of all, DWARF 2.0 reached non-draft form, so i'm not sure why
they use a draft version of the standard.
> Just to see if its a quick fix that could be made, I was wondering if
> anyone
> knows the exact document GDB's DWARF abilities are based on.
>
GDB supports DWARF 2.0, as well as some of the draft DWARF 3.0.
Please send a binary made with openwatcom so we can look at it and see
what's up.
>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2003-09-26 21:36 UTC | newest]
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2003-09-25 2:02 GDB without traditional frames Andrew Cagney
2003-09-25 14:45 ` Andrew Cagney
2003-09-26 21:36 ` y2bismil
2003-09-26 21:54 ` Daniel Berlin
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