From: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Jan Kara <jack@suse.cz>, LKML <linux-kernel@vger.kernel.org>,
pmladek@suse.cz, Frederic Weisbecker <fweisbec@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH 8/8] printk: Add config option for disabling printk offloading
Date: Tue, 22 Apr 2014 11:22:59 +0100 [thread overview]
Message-ID: <20140422112259.5f106a44@alan.etchedpixels.co.uk> (raw)
In-Reply-To: <20140418115438.1e65e07af17e3ba6d7c554db@linux-foundation.org>
On Fri, 18 Apr 2014 11:54:38 -0700
Andrew Morton <akpm@linux-foundation.org> wrote:
> On Wed, 26 Mar 2014 20:28:15 +0100 Jan Kara <jack@suse.cz> wrote:
>
> > > All the afflicted consoles are serial, all go via the uart layer as far
> > > as I can see.
> > >
> > > The uart layer has a queue mechanism that could be used
> > I'm sorry, I don't follow here - what can the uart queueing be used for?
>
> Alan, I'm desperate to avoid adding all this complexity to core printk
> code to solve such a rare problem. It'd be great if you could flesh out
> any alternative ideas please.
It's not worth adding for upstream anyway - not in that form. If it just
used schedule_work it would be way way cleaner anyway.
For the general buffering case we already have tty_write_message(). It's
only really intended for use by the old quota code so it's currently
assuming nul terminated string but thats a trivial detail.
For that matter I don't see why such systems can't implement a queuecon
console which is a queue on the printk side and a fifo on the userspace
side.
The implementation then becomes trivial.
If you want reliable crash logging then we need to be able to set a
printk level mask per console and just set the serial console for
"crit/err" and the queue console for the rest, with a 'cat
>/dev/ttywhatever' running if this feature was in use ?
Alan
next prev parent reply other threads:[~2014-04-22 10:23 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-25 17:54 [PATCH 0/8 v4] printk: Cleanups and softlockup avoidance Jan Kara
2014-03-25 17:54 ` [PATCH 1/8] printk: Remove outdated comment Jan Kara
2014-03-25 17:54 ` [PATCH 2/8] printk: Release lockbuf_lock before calling console_trylock_for_printk() Jan Kara
2014-04-23 20:56 ` Andrew Morton
2014-04-24 10:18 ` Jan Kara
2014-03-25 17:54 ` [PATCH 3/8] printk: Enable interrupts " Jan Kara
2014-03-25 17:54 ` [PATCH 4/8] printk: Remove separate printk_sched buffers and use printk buf instead Jan Kara
2014-05-05 18:37 ` Steven Rostedt
2014-03-25 17:54 ` [PATCH 5/8] printk: Hand over printing to console if printing too long Jan Kara
2014-03-25 17:54 ` [PATCH 6/8] printk: Start printing handover kthreads on demand Jan Kara
2014-03-26 17:16 ` One Thousand Gnomes
2014-03-26 19:06 ` Jan Kara
2014-03-25 17:55 ` [PATCH 7/8] kernel: Avoid softlockups in stop_machine() during heavy printing Jan Kara
2014-03-25 17:55 ` [PATCH 8/8] printk: Add config option for disabling printk offloading Jan Kara
2014-03-26 17:23 ` One Thousand Gnomes
2014-03-26 19:28 ` Jan Kara
2014-04-18 18:54 ` Andrew Morton
2014-04-22 10:22 ` One Thousand Gnomes [this message]
2014-04-23 11:08 ` Jan Kara
2014-04-23 12:35 ` One Thousand Gnomes
2014-04-23 14:29 ` Jan Kara
2014-04-23 18:17 ` Andrew Morton
2014-04-23 21:16 ` One Thousand Gnomes
2014-04-23 21:41 ` Jiri Kosina
2014-04-24 14:00 ` One Thousand Gnomes
2014-05-15 21:28 ` Jan Kara
2014-04-23 9:30 ` Jan Kara
2014-04-08 14:27 ` [PATCH 0/8 v4] printk: Cleanups and softlockup avoidance Jan Kara
2014-04-08 19:02 ` Andrew Morton
-- strict thread matches above, loose matches on Subject: below --
2014-03-14 16:21 [PATCH 0/8 v3] " Jan Kara
2014-03-14 16:21 ` [PATCH 8/8] printk: Add config option for disabling printk offloading Jan Kara
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