Message-ID: <cc36310a-c390-42f0-9c82-5b0236a9abfa@broadcom.com>
Date: Fri, 27 Jun 2025 09:09:53 -0700
From: Florian Fainelli <florian.fainelli@...adcom.com>
To: Jan Kara <jack@...e.cz>
Cc: "Liam R. Howlett" <Liam.Howlett@...cle.com>,
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Subject: Re: [PATCH 00/16] MAINTAINERS: Include GDB scripts under their
 relevant subsystems

On 6/27/25 00:55, Jan Kara wrote:
> On Thu 26-06-25 09:39:36, Florian Fainelli wrote:
>> On 6/26/25 09:17, Liam R. Howlett wrote:
>>> * Florian Fainelli <florian.fainelli@...adcom.com> [250625 19:13]:
>>>> Linux has a number of very useful GDB scripts under scripts/gdb/linux/*
>>>> that provide OS awareness for debuggers and allows for debugging of a
>>>> variety of data structures (lists, timers, radix tree, mapletree, etc.)
>>>> as well as subsystems (clocks, devices, classes, busses, etc.).
>>>>
>>>> These scripts are typically maintained in isolation from the subsystem
>>>> that they parse the data structures and symbols of, which can lead to
>>>> people playing catch up with fixing bugs or updating the script to work
>>>> with updates made to the internal APIs/objects etc. Here are some
>>>> recents examples:
>>>>
>>>> https://lore.kernel.org/all/20250601055027.3661480-1-tony.ambardar@gmail.com/
>>>> https://lore.kernel.org/all/20250619225105.320729-1-florian.fainelli@broadcom.com/
>>>> https://lore.kernel.org/all/20250625021020.1056930-1-florian.fainelli@broadcom.com/
>>>>
>>>> This patch series is intentionally split such that each subsystem
>>>> maintainer can decide whether to accept the extra
>>>> review/maintenance/guidance that can be offered when GDB scripts are
>>>> being updated or added.
>>>
>>> I don't see why you think it was okay to propose this in the way you
>>> have gone about it.  Looking at the mailing list, you've been around for
>>> a while.
>>
>> This should probably have been posted as RFC rather than PATCH, but as I
>> indicate in the cover letter this is broken down to allow maintainers like
>> yourself to accept/reject
>>
>>>
>>> The file you are telling me about seems to be extremely new and I needed
>>> to pull akpm/mm-new to discover where it came from.. because you never
>>> Cc'ed me on the file you are asking me to own.
>>
>> Yes, that file is very new indeed, and my bad for not copying you on it.
>>
>> I was not planning on burning an entire day worth of work to transition the
>> GDB scripts dumping the interrupt tree away from a radix tree to a maple
>> tree. All of which happens with the author of that conversion having
>> absolutely no idea that broke anything in the tree because very few people
>> know about the Python GDB scripts that Linux has. It is not pleasant to be
>> playing catch when it would have take maybe an extra couple hours for
>> someone intimately familiar with the maple tree to come up with a suitable
>> implementation replacement for mtree_load().
>>
>> So having done it felt like there is a maintenance void that needs to be
>> filled, hence this patch set.
> 
> I can see that it takes a lot of time to do a major update of a gdb
> debugging script after some refactoring like this. OTOH mandating some gdb
> scripts update is adding non-trivial amount of work to changes that are
> already hard enough to do as is. 

This really should have been posted as RFC, because I can see how 
posting this as PATCH would be seen as coercing maintainers into taking 
those GDB scripts under their umbrella.

> And the obvious question is what is the
> value? I've personally never used these gdb scripts and never felt a strong
> need for something like that. People have various debugging aids (like BPF
> scripts, gdb scripts, there's crash tool and drgn, and many more) lying
> around. 

Those are valuable tools in the tool box, but GDB scripts can work when 
your only debug tool accessible is JTAG for instance, I appreciate this 
is typically miles away from what most of the kernel community does, but 
this is quite typical and common in embedded systems. When you operate 
in that environment, having a decent amount of debugger awareness of 
what is being debugged is immensely valuable in saving time.

> I'm personally of an opinion that it is not a responsibility of
> the person doing refactoring to make life easier for them or even fixing
> them and I don't think that the fact that some debug aid is under
> scripts/gdb/ directory is making it more special. 

That is really the question that I am trying to get answered with this 
patch series. IMHO as a subsystem maintainer it is not fair to be 
completely oblivious to scripts that live in the source tree, even if 
you are not aware of those.

 > So at least as far as I'm> concerned (VFS, fsnotify and other 
filesystem related stuff) I don't plan
> on requiring updates to gdb scripts from people doing changes or otherwise
> actively maintain them.

vfs.py script is beyond trivial, the largest and most complicated IMHO 
is mapletree.py which had to be recently developed to continue to 
support parsing the interrupt descriptor tree in the kernel, I can 
maintain that one now that I know a lot more than I ever wished I knew 
about maple trees. So really the burden is not as big as it may seem but 
it's fair not to be taking on more work as a maintainer, I get that.

Thanks for your feedback!
-- 
Florian

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