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    SubjectRe: [PATCH] tracing: add trace console
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    Date
    [ Added Peter, Thomas and Andrew ]

    On Wed, 2011-11-16 at 11:18 +0100, Johannes Berg wrote:
    > From: Johannes Berg <johannes.berg@intel.com>
    >
    > As described in the Kconfig entry, logging printk
    > output is useful to correlate (existing) printk
    > debugging with (existing) tracing. The easiest way
    > to achieve this is to register a console that just
    > calls trace_printk(), which this module does.

    I'm good with this. Anyone have any issues with it?

    -- Steve

    >
    > Signed-off-by: Johannes Berg <johannes.berg@intel.com>
    > ---
    > kernel/trace/Kconfig | 13 ++++++++++
    > kernel/trace/Makefile | 2 +
    > kernel/trace/trace-console.c | 55 +++++++++++++++++++++++++++++++++++++++++++
    > 3 files changed, 70 insertions(+)
    >
    > --- a/kernel/trace/Kconfig 2011-11-16 11:11:27.000000000 +0100
    > +++ b/kernel/trace/Kconfig 2011-11-16 11:11:35.000000000 +0100
    > @@ -368,6 +368,19 @@ config BLK_DEV_IO_TRACE
    >
    > If unsure, say N.
    >
    > +config TRACE_CONSOLE
    > + tristate "Support for a tracing console"
    > + help
    > + Say M (or Y if you must, but this is not recommended) to be able
    > + to get a tracing console that puts every kernel message into the
    > + tracing infrastructure using trace_printk(). This is useful to
    > + correlate (existing) printk debugging with tracing. When using it
    > + remember to set the console level, e.g. with "dmesg -n8".
    > +
    > + The module is called trace-console.
    > +
    > + Say N if unsure.
    > +
    > config KPROBE_EVENT
    > depends on KPROBES
    > depends on HAVE_REGS_AND_STACK_ACCESS_API
    > --- a/kernel/trace/Makefile 2011-11-16 11:11:27.000000000 +0100
    > +++ b/kernel/trace/Makefile 2011-11-16 11:11:35.000000000 +0100
    > @@ -62,4 +62,6 @@ ifeq ($(CONFIG_TRACING),y)
    > obj-$(CONFIG_KGDB_KDB) += trace_kdb.o
    > endif
    >
    > +obj-$(CONFIG_TRACE_CONSOLE) += trace-console.o
    > +
    > libftrace-y := ftrace.o
    > --- /dev/null 1970-01-01 00:00:00.000000000 +0000
    > +++ b/kernel/trace/trace-console.c 2011-11-16 11:11:35.000000000 +0100
    > @@ -0,0 +1,55 @@
    > +/*
    > + * Copyright (c) 2011 Intel Corporation. All rights reserved.
    > + *
    > + * This program is free software; you can redistribute it and/or modify
    > + * it under the terms of the GNU General Public License as published by
    > + * the Free Software Foundation; either version 2 of the License, or
    > + * (at your option) any later version.
    > + *
    > + * This program is distributed in the hope that it will be useful,
    > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
    > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    > + * GNU General Public License for more details.
    > + *
    > + * You should have received a copy of the GNU General Public License
    > + * along with this program; if not, write to the Free Software
    > + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
    > + *
    > + * The full GNU General Public License is included in this distribution in
    > + * the file called COPYING.
    > + *
    > + * Author: Johannes Berg <johannes.berg@intel.com>
    > + */
    > +#include <linux/init.h>
    > +#include <linux/module.h>
    > +#include <linux/console.h>
    > +
    > +MODULE_AUTHOR("Johannes Berg <johannes.berg@intel.com>");
    > +MODULE_DESCRIPTION("Console driver for tracing");
    > +MODULE_LICENSE("GPL");
    > +
    > +
    > +static void trace_msg(struct console *con, const char *msg, unsigned int len)
    > +{
    > + trace_printk("%*s", len, msg);
    > +}
    > +
    > +static struct console traceconsole = {
    > + .name = "tracecon",
    > + .flags = CON_ENABLED,
    > + .write = trace_msg,
    > +};
    > +
    > +static int __init init_traceconsole(void)
    > +{
    > + register_console(&traceconsole);
    > + return 0;
    > +}
    > +
    > +static void __exit exit_traceconsole(void)
    > +{
    > + unregister_console(&traceconsole);
    > +}
    > +
    > +module_init(init_traceconsole);
    > +module_exit(exit_traceconsole);
    >




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