On Fri, Aug 20, 2021 at 10:30 AM David Laight [off-list ref] wrote:

From: Linus Torvalds

quoted

Sent: 19 August 2021 23:33

On Thu, Aug 19, 2021 at 2:43 PM Jeff Layton [off-list ref] wrote:

quoted

What sort of big, ugly warning did you have in mind?

I originally thought WARN_ON_ONCE() just to get the distro automatic
error handling involved, but it would probably be a big problem for
the people who end up having panic-on-warn or something.

Even panic-on-oops is a PITA.
Took us weeks to realise that a customer system that was randomly
rebooting was 'just' having a boring NULL pointer access.

quoted

So probably just a "make it a big box" thing that stands out, kind of
what lockdep etc does with

        pr_warn("======...====\n");

around the messages..

Do we really need more of these?
They take time to print (especially on serial
consoles) and increase kernel size.

What's wrong with using an appropriate KERN_*, and letting userspace
make sure the admin/user will see the message (see below)?

quoted

I don't know if distros have some pattern we could use that would end
up being something that gets reported to the user?

Will users even see it?
A lot of recent distro installs try very hard to hide all the kernel
messages.

Exactly.  E.g. Ubuntu doesn't show any kernel output during normal
operation.

On Fri, Aug 20, 2021 at 6:12 PM Linus Torvalds
[off-list ref] wrote:

On Fri, Aug 20, 2021 at 6:43 AM Steven Rostedt [off-list ref] wrote:

quoted

On Thu, 19 Aug 2021 15:32:31 -0700
Linus Torvalds [off-list ref] wrote:

quoted

I don't know if distros have some pattern we could use that would end
up being something that gets reported to the user?

So what would be more interesting is if there's some distro support
for showing kernel notifications..

I see new notifications for calendar events, for devices that got
mounted, for a lot of things - so I'm really wondering if somebody
already perhaps had something for specially formatted kernel
messages..

Isn't that what the old syslog and the new systemd are supposed to
handle in userspace?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds