[Crash-utility] [PATCH] printk: add support for lockless ringbuffer

[HAGIO KAZUHITO(萩尾 一仁)]

Hi John, Lianbo,

-----Original Message-----
> On 2020-11-20, HAGIO KAZUHITO(萩尾　一仁)	<k-hagio-ab at nec.com> wrote:
> > I've updated John's RFC crash patch to match 5.10-rc4 kernel.
> > Changes from the RFC patch:
> > - followed the following kernel commits
> >     cfe2790b163a ("printk: move printk_info into separate array")
> >     74caba7f2a06 ("printk: move dictionary keys to dev_printk_info")
> >     f35efc78add6 ("printk: remove dict ring")
> > - moved the added members in offset_table and size_table to the end
> >   of them
> > - print offsets and sizes with "help -o" option
> > - support "log -T" option
> 
> Thank you for this work. I've attached a followup "crash" patch to
> correctly interpret the state value. With this followup patch applied,
> this passes all my tests.

Thank you for the patch.  It looks good and tested OK also at my end.

Acked-by: Kazuhito Hagio <k-hagio-ab at nec.com>

Lianbo, could you review these two patches?

> 
> Note that support for "./crash --log ./vmcore" is still not
> implemented. That can be done in a separate patch.

Yes, no problem for now.

Personally I think it might be fine to deprecate the "crash --log" option
because IIRC it doesn't support a dynamically allocated ringbuffer (log_buf)
in the first place, and it will need some work to support it.

So need more discussion if we support it.

Thanks,
Kazu