[PATCH] arm64: kexec: flush log to console in nmi_panic()

[Will Deacon]

On Thu, Jun 17, 2021 at 01:55:08PM -0400, Pavel Tatashin wrote:
> On Thu, Jun 17, 2021 at 1:52 PM Will Deacon <will at kernel.org> wrote:
> >
> > On Thu, Jun 17, 2021 at 12:50:23PM +0000, Huang Shijie wrote:
> > > If kdump is configured, nmi_panic() may run to machine_kexec().
> > >
> > > But in NMI context, the log is put in PER-CPU nmi_print_seq.
> > > So we can not see any log on the console since we entered the NMI context,
> > > such as the "Bye!" in previous line.
> > >
> > > This patch fixes this issue by two steps:
> > >       1) Uses printk_safe_flush_on_panic() to flush the log from
> > >              nmi_print_seq to global printk ring buffer,
> > >         2) Then uses console_flush_on_panic() to flush to console.
> > >
> > > After this patch, we can see the "Bye!" log in the panic console.
> >
> > Does it matter? I'd be more inclined to remove the print altogether...
> 
> I agree, the print could be removed entirely. But, my assumption was
> that this patch meant to flush other buffered prints beside this last
> "Bye" one.

That sounds like something which should be done in the core code, rather
than the in the architecture backend (and looks like panic() might do this
already?)

Will