On Sun, Mar 29, 2020 at 4:48 PM Chen Yu <yu.c.chen@xxxxxxxxx> 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'.
>
> Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
> Cc: Len Brown <lenb@xxxxxxxxxx>
> Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
> Signed-off-by: Chen Yu <yu.c.chen@xxxxxxxxx>
> ---
> v2: According to Randy's suggestion, add the command line
> option to Documentation/admin-guide/kernel-parameters.txt
> ---
> Documentation/admin-guide/kernel-parameters.txt | 3 +++
> kernel/power/main.c | 7 +++++++
> 2 files changed, 10 insertions(+)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index c07815d230bc..105ec73743d7 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -3698,6 +3698,9 @@
> Override pmtimer IOPort with a hex value.
> e.g. pmtmr=0x508
>
> + pm_debug_message [SUSPEND,KNL]
> + Enable suspend/resume debug messages during boot up.
> +
> pnp.debug=1 [PNP]
> Enable PNP debug messages (depends on the
> CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
> 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);
I'd call this "pm_debug_messages" (just like the sysfs knob) and
rename the rest accordingly.
> +
> /**
> * __pm_pr_dbg - Print a suspend debug message to the kernel log.
> * @defer: Whether or not to use printk_deferred() to print the message.
> --
