Re: [PATCH 6/9] gdb: Implement 'bt shadow' to print the shadow stack backtrace.

[Guinevere Larsen <guinevere@redhat.com>]

On 11/3/25 4:47 PM, Schimpe, Christina wrote:
>> -----Original Message-----
>> From: Guinevere Larsen <guinevere@redhat.com>
>> Sent: Mittwoch, 29. Oktober 2025 16:28
>> To: Schimpe, Christina <christina.schimpe@intel.com>; 'Simon Marchi'
>> <simark@simark.ca>; 'Eli Zaretskii' <eliz@gnu.org>
>> Cc: 'gdb-patches@sourceware.org' <gdb-patches@sourceware.org>;
>> 'thiago.bauermann@linaro.org' <thiago.bauermann@linaro.org>
>> Subject: Re: [PATCH 6/9] gdb: Implement 'bt shadow' to print the shadow stack
>> backtrace.
>>
>> On 10/29/25 12:05 PM, Schimpe, Christina wrote:
>>> Kindly pinging for feedback on this discussion to clarify if we should
>>> better use
>>> - "bt -shadow" (command line option)
>>> - "bt shadow" (subcommand approach, current implementation).
>>>
>>> My personal opinion is still to use the subcommand approach, but, as I
>>> already said, I think "bt -shadow" would be fine, too.
>>>
>>> Please also see this discussion with Thiago:
>>> https://sourceware.org/pipermail/gdb-patches/2025-October/221660.html
>> If it makes any difference, I personally prefer the command line option
>> approach. That's based on looking at how record, record full and record btrace
>> works, it is much easier to understand the code if the decision is made on the
>> command's function itself
> Hi Guinevere,
>
> I might be missing something here. Aren’t record, record full, and record btrace considered subcommands?
> If that’s the case, wouldn’t the example of the record command actually support the subcommand approach? Or are you pointing to record as a negative example?

I am using it as a negative example, yes, sorry if it was confusing.

record full and record btrace are subcommands of record, and I found it 
needlessly confusing to figure out how the code decided what to do. I 
didn't even know that commands with subcommands were supported to be 
quite honest, so I expected "full" and "btrace" to be handled like 
options, and was quite confused when that wasn't the case.

>
> About your comment:
> "it is much easier to understand the code if the decision is made on the command's function itself"
> Could you clarify what you mean? Are you referring to making it easier for a reviewer or developer to go through my patches?
>  From my perspective, the most important thing is that the GDB user can find the subcommand or command-line option easily and intuitively.

I mean making it easier to maintain as a GDB developer, yes. However, I 
do think this will also make things more confusing to end-users. Right 
now, backtrace accepts '-' prefixed options and a few non '-' prefixed 
options for backwards compatibility. from the POV of an end-user who 
doesn't know the difference between a command option and a subcommand, 
you'd be introducing a new option in the backwards compatible (but not 
preferred) style. Or worse, they'd think that "backtrace full", 
"backtrace no-filters" and "backtrace hide" were also subcommands but 
now the list of backtrace subcommands would no longer show those,  which 
makes it sound like they stopped being supported or that the help text 
is incorrect.

-- 
Cheers,
Guinevere Larsen
It/she


>
> Looking forward to your thoughts!
> Christina
> Intel Deutschland GmbH
> Registered Address: Dornacher Straße 1, 85622 Feldkirchen, Germany
> Tel: +49 89 991 430, www.intel.de
> Managing Directors: Harry Demas, Jeffrey Schneiderman, Yin Chong Sorrell
> Chairperson of the Supervisory Board: Nicole Lau
> Registered Seat: Munich
> Commercial Register: Amtsgericht München HRB 186928
>