Re: [PATCH qemu 2/2] dump: Only use the makedumpfile flattened format when necessary

[Omar Sandoval]

On Tue, Sep 12, 2023 at 10:34:04AM +0400, Marc-André Lureau wrote:
> Hi
> 
> On Wed, Aug 23, 2023 at 2:03 PM Marc-André Lureau
> <marcandre.lureau@gmail.com> wrote:
> >
> > Hi
> >
> > On Wed, Aug 23, 2023 at 4:31 AM Stephen Brennan
> > <stephen.s.brennan@oracle.com> wrote:
> > >
> > > Stephen Brennan <stephen.s.brennan@oracle.com> writes:
> > > > Marc-André Lureau <marcandre.lureau@gmail.com> writes:
> > > >> I am a bit reluctant to change the dump format by default. But since 
> > > >> the
> > > >> flatten format is more "complicated" than the "normal" format, perhaps 
> > > >> we
> > > >> can assume all users will handle it.
> > > >>
> > > >> The change is probably late for 8.1 though..
> > > >
> > > > Thank you for your review and testing!
> > > >
> > > > I totally understand the concern about making the change by default. I
> > > > do believe that nobody should notice too much because the normal format
> > > > should be easier to work with, and more broadly compatible. I don't know
> > > > of any tool which deals with the flattened format that can't handle the
> > > > normal format, except for "makedumpfile -R" itself.
> > > >
> > > > If it's a blocker, I can go ahead and add a new flag to the command to
> > > > enable the behavior. However there are a few good justifications not to
> > > > add a new flag. I think it's going to be difficult to explain the
> > > > difference between the two formats in documentation, as the
> > > > implementation of the formats is a bit "into the weeds". The libvirt API
> > > > also specifies each format separately (kdump-zlib, kdump-lzo,
> > > > kdump-snappy) and so adding several new options there would be
> > > > unfortunate for end-users as well.
> > > >
> > > > At the end of the day, it's your judgment call, and I'll implement it
> > > > how you prefer.
> > >
> > > I just wanted to check back on this to clarify the next step. Are you
> > > satisfied with this and waiting to apply it until the right time? Or
> > > would you prefer me to send a new version making this opt-in?
> > >
> >
> > Nobody seems to raise concerns. If it would be just me, I would change
> > it. But we should rather be safe, so let's make it this opt-in please.
> >
> >
> 
> Alex, Daniel, Thomas .. Do you have an opinion on changing the dump format?

Chiming in as a user here, but I'd much prefer for the normal format to
be the default. The last time that I tried dump-guest-memory with the
kdump format, it took me awhile to figure out what format it was
actually using since libkdumpfile didn't understand it.