Re: [PATCH V3] watchdog: hpwdt: Adjust documentation to match latest kernel module parameters

[Guenter Roeck <linux@roeck-us.net>]

On 04/06/2016 06:11 PM, Croxon, Nigel wrote:
> From: Nigel Croxon <nigel.croxon@hpe.com>
> Date: Wed, 6 Apr 2016 14:40:05 -0400
> Subject: [PATCH V3] watchdog: hpwdt: Adjust documentation to match latest kernel module parameters.
>
> Adjust documentation to match latest kernel module parameters.
>
> V3 - Fixed two spelling mistakes.
> V2 - Changed insmod / rmmod to modprobe / modprobe -r
>
> Signed-off-by: Nigel Croxon <nigel.croxon@hpe.com>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

> ---
>   Documentation/watchdog/hpwdt.txt |   57 ++++++++++++++++++++------------------
>   1 files changed, 30 insertions(+), 27 deletions(-)
>
> diff --git a/Documentation/watchdog/hpwdt.txt b/Documentation/watchdog/hpwdt.txt
> index 9488078..3521e8b 100644
> --- a/Documentation/watchdog/hpwdt.txt
> +++ b/Documentation/watchdog/hpwdt.txt
> @@ -1,64 +1,67 @@
> -Last reviewed: 06/02/2009
> +Last reviewed: 04/04/2016
>
> -                     HP iLO2 NMI Watchdog Driver
> -              NMI sourcing for iLO2 based ProLiant Servers
> +                     HPE iLO NMI Watchdog Driver
> +              NMI sourcing for iLO based ProLiant Servers
>                        Documentation and Driver by
> -              Thomas Mingarelli <thomas.mingarelli@hp.com>
> +              Thomas Mingarelli <thomas.mingarelli@hpe.com>
>
> - The HP iLO2 NMI Watchdog driver is a kernel module that provides basic
> + The HPE iLO NMI Watchdog driver is a kernel module that provides basic
>    watchdog functionality and the added benefit of NMI sourcing. Both the
>    watchdog functionality and the NMI sourcing capability need to be enabled
>    by the user. Remember that the two modes are not dependent on one another.
>    A user can have the NMI sourcing without the watchdog timer and vice-versa.
> + All references to iLO in this document imply it also works on iLO2 and all
> + subsequent generations.
>
>    Watchdog functionality is enabled like any other common watchdog driver. That
>    is, an application needs to be started that kicks off the watchdog timer. A
>    basic application exists in the Documentation/watchdog/src directory called
>    watchdog-test.c. Simply compile the C file and kick it off. If the system
> - gets into a bad state and hangs, the HP ProLiant iLO 2 timer register will
> + gets into a bad state and hangs, the HPE ProLiant iLO timer register will
>    not be updated in a timely fashion and a hardware system reset (also known as
>    an Automatic Server Recovery (ASR)) event will occur.
>
> - The hpwdt driver also has four (4) module parameters. They are the following:
> + The hpwdt driver also has three (3) module parameters. They are the following:
>
> - soft_margin - allows the user to set the watchdog timer value
> - allow_kdump - allows the user to save off a kernel dump image after an NMI
> + soft_margin - allows the user to set the watchdog timer value.
> +               Default value is 30 seconds.
> + allow_kdump - allows the user to save off a kernel dump image after an NMI.
> +               Default value is 1/ON
>    nowayout    - basic watchdog parameter that does not allow the timer to
>                  be restarted or an impending ASR to be escaped.
> - priority    - determines whether or not the hpwdt driver is first on the
> -               die_notify list to handle NMIs or last. The default value
> -               for this module parameter is 0 or LAST. If the user wants to
> -               enable NMI sourcing then reload the hpwdt driver with
> -               priority=1 (and boot with nmi_watchdog=0).
> +               Default value is set when compiling the kernel. If it is set
> +               to "Y", then there is no way of disabling the watchdog once
> +               it has been started.
>
>    NOTE: More information about watchdog drivers in general, including the ioctl
>          interface to /dev/watchdog can be found in
>          Documentation/watchdog/watchdog-api.txt and Documentation/IPMI.txt.
>
> - The priority parameter was introduced due to other kernel software that relied
> - on handling NMIs (like oprofile). Keeping hpwdt's priority at 0 (or LAST)
> - enables the users of NMIs for non critical events to be work as expected.
> -
>    The NMI sourcing capability is disabled by default due to the inability to
>    distinguish between "NMI Watchdog Ticks" and "HW generated NMI events" in the
>    Linux kernel. What this means is that the hpwdt nmi handler code is called
>    each time the NMI signal fires off. This could amount to several thousands of
>    NMIs in a matter of seconds. If a user sees the Linux kernel's "dazed and
>    confused" message in the logs or if the system gets into a hung state, then
> - the hpwdt driver can be reloaded with the "priority" module parameter set
> - (priority=1).
> + the hpwdt driver can be reloaded.
>
>    1. If the kernel has not been booted with nmi_watchdog turned off then
> -    edit /boot/grub/menu.lst and place the nmi_watchdog=0 at the end of the
> -    currently booting kernel line.
> +    edit and place the nmi_watchdog=0 at the end of the currently booting
> +    kernel line. Depending on your Linux distribution and platform setup:
> +    For non-UEFI systems
> +       /boot/grub/grub.conf   or
> +       /boot/grub/menu.lst
> +    For UEFI systems
> +      /boot/efi/EFI/distroname/grub.conf   or
> +      /boot/efi/efi/distroname/elilo.conf
>    2. reboot the sever
> - 3. Once the system comes up perform a rmmod hpwdt
> - 4. insmod /lib/modules/`uname -r`/kernel/drivers/char/watchdog/hpwdt.ko priority=1
> + 3. Once the system comes up perform a modprobe -r hpwdt
> + 4. modprobe /lib/modules/`uname -r`/kernel/drivers/watchdog/hpwdt.ko
>
>    Now, the hpwdt can successfully receive and source the NMI and provide a log
> - message that details the reason for the NMI (as determined by the HP BIOS).
> + message that details the reason for the NMI (as determined by the HPE BIOS).
>
> - Below is a list of NMIs the HP BIOS understands along with the associated
> + Below is a list of NMIs the HPE BIOS understands along with the associated
>    code (reason):
>
>   	No source found                00h
> @@ -92,4 +95,4 @@ Last reviewed: 06/02/2009
>
>
>    -- Tom Mingarelli
> -    (thomas.mingarelli@hp.com)
> +    (thomas.mingarelli@hpe.com)
>