[PATCH] makedumpfile: printk: add support for lockless ringbuffer

[HAGIO KAZUHITO(萩尾 一仁)]

-----Original Message-----
> On 2020-11-19, HAGIO KAZUHITO(萩尾　一仁)	<k-hagio-ab at nec.com> wrote:
> > From: John Ogness <john.ogness at linutronix.de>
> >
> > Linux 5.10 introduces a new lockless ringbuffer.  The new ringbuffer
> > is structured completely different to the previous iterations.
> > Add support for retrieving the ringbuffer from debug information
> > and/or using vmcoreinfo.  The new ringbuffer is detected based on
> > the availability of the "prb" symbol.
> >
> > Signed-off-by: John Ogness <john.ogness at linutronix.de>
> > Signed-off-by: Kazuhito Hagio <k-hagio-ab at nec.com>
> > ---
> > I've updated John's RFC makedumpfile patch to match 5.10-rc4 kernel.
> > Changes from the RFC patch:
> > - followed the following kernel commit
> >     cfe2790b163a ("printk: move printk_info into separate array")
> > - divided members of struct printk_log in offset_table into each structure
> >   for readability
> > - added some error handlings
> > - also dump head record that was missed
> 
> I confirm that these changes are correct. Thanks for updating this,
> adding the needed error handling, and catching that the head record was
> missed!

Hi John,

Thank you for confirming and testing.
I will merge this after a few slight fixes and more tests.

I've updated your crash patch [1] as well, it would be helpful if you
would check it.
[1] https://www.redhat.com/archives/crash-utility/2020-November/msg00065.html

Thanks,
Kazu