linux-kernel - Re: [PATCH] PM / sleep: Add pm_debug

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Message-ID: <a9843786-e7da-2c3c-30e2-c4887e9af4c6@infradead.org>
Date:   Fri, 27 Mar 2020 08:39:44 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Chen Yu <yu.c.chen@...el.com>, linux-pm@...r.kernel.org
Cc:     Pavel Machek <pavel@....cz>, linux-kernel@...r.kernel.org,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: Re: [PATCH] PM / sleep: Add pm_debug_messages boot command control

On 3/27/20 4:11 AM, Chen Yu wrote:
> Debug messages from the system suspend/hibernation infrastructure
> is disabled by default, and can only be enabled after the system
> has boot up via /sys/power/pm_debug_messages. This makes the hibernation
> resume hard to track as it involves system boot up across hibernation.
> There's no chance for software_resume() to track the resume process,
> eg.
> 
> Turning on the pm_debug_messages during boot up by appending
> 'pm_debug_message'.

Please add that command line option to
Documentation/admin-guide/kernel-parameters.txt.
Thanks.

> Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
> Cc: Len Brown <lenb@...nel.org>
> Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Signed-off-by: Chen Yu <yu.c.chen@...el.com>
> ---
>  kernel/power/main.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/kernel/power/main.c b/kernel/power/main.c
> index 69b7a8aeca3b..1da3d7c15e03 100644
> --- a/kernel/power/main.c
> +++ b/kernel/power/main.c
> @@ -535,6 +535,13 @@ static ssize_t pm_debug_messages_store(struct kobject *kobj,
>  
>  power_attr(pm_debug_messages);
>  
> +static int __init pm_debug_message_setup(char *str)
> +{
> +	pm_debug_messages_on = true;
> +	return 1;
> +}
> +__setup("pm_debug_message", pm_debug_message_setup);
> +
>  /**
>   * __pm_pr_dbg - Print a suspend debug message to the kernel log.
>   * @defer: Whether or not to use printk_deferred() to print the message.
> 


-- 
~Randy
Reported-by: Randy Dunlap <rdunlap@...radead.org>