[0/3] scripts/qemu-gdb: Make coroutine dumps to work with coredumps

Message

Peter Xu Dec. 11, 2024, 8:17 p.m. UTC

Coroutines are used in many cases in block layers. It's also used in live
migration when on destination side, and it'll be handy to diagnose crashes
within a coroutine when we want to also know what other coroutines are
doing.

This series adds initial support for that, not pretty but it should start
working.  Since we can't use the trick to modify registers on the fly in
non-live gdb sessions, we do manual unwinds.

Thanks,

Peter Xu (3):
  scripts/qemu-gdb: Always do full stack dump for python errors
  scripts/qemu-gdb: Simplify fs_base fetching for coroutines
  scripts/qemu-gdb: Support coroutine dumps in coredumps

 scripts/qemu-gdb.py          |  2 +
 scripts/qemugdb/coroutine.py | 73 ++++++++++++++++++++++--------------
 2 files changed, 47 insertions(+), 28 deletions(-)

Comments

Fabiano Rosas Dec. 11, 2024, 8:25 p.m. UTC | #1

Peter Xu <[e-mail]> writes:

> Coroutines are used in many cases in block layers. It's also used in live
> migration when on destination side, and it'll be handy to diagnose crashes
> within a coroutine when we want to also know what other coroutines are
> doing.

Not sure if you've seen this message on the list:

https://lore.kernel.org/r/[e-mail]

Peter Xu Dec. 11, 2024, 9:39 p.m. UTC | #2

On Wed, Dec 11, 2024 at 05:25:10PM -0300, Fabiano Rosas wrote:
> Peter Xu <[e-mail]> writes:
> 
> > Coroutines are used in many cases in block layers. It's also used in live
> > migration when on destination side, and it'll be handy to diagnose crashes
> > within a coroutine when we want to also know what other coroutines are
> > doing.
> 
> Not sure if you've seen this message on the list:
> 
> https://lore.kernel.org/r/[e-mail]

No I didn't.  I only started looking at this because I got a bug a few days
ago that I need to look at the main coroutine where dest crashed, then
Stefan told me this script and also told me it only works with live session.
Ideally I'll need coredump debug-ability, then I figured it isn't too hard.

I saw that it didn't yet land gdb, and it's much more involved even if it
could be more generic.  Not sure how the block developers think, personally
I prefer this much smaller change because it works on old systems, where I
can easily install gdb with package managers.