From: Guenter Roeck <linux@roeck-us.net>
To: Francois-Nicolas Muller <francois-nicolas.muller@intel.com>
Cc: wim@iguana.be, linux-watchdog@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] TCO watchdog pretimeout handler
Date: Tue, 16 Jun 2015 22:14:57 -0700 [thread overview]
Message-ID: <55810251.6070106@roeck-us.net> (raw)
In-Reply-To: <1434462314-17298-1-git-send-email-francois-nicolas.muller@intel.com>
On 06/16/2015 06:45 AM, Francois-Nicolas Muller wrote:
> Use TCO watchdog first timeout (pretimeout) to dump CPU backtraces
> and ease debug of watchdog expiration causes.
> TCO logic generates a SCI interrupt, then its handler dumps all CPU
> backtraces and calls panic (in order to execute registered panic
> callbacks).
> SCI interrupt number (GPE) is configured from ACPI tables.
>
> Signed-off-by: Francois-Nicolas Muller <francois-nicolas.muller@intel.com>
> ---
> Thanks Guenter for your review.
>
>> If I recall correctly, the iTCO watchdog can also generate an NMI.
>> Would it make sense to add support for handling this NMI as well ?
>
> As far as I know, there is no NMI option for TCO watchdog interrupt.
> Do you have any documentation about this ?
>
Actually that was a miscommunication, sorry. I confused it waith another watchdog.
I assume you took out all mention of SMI because it is not (yet) supported.
Would be interesting to know what systems out there actually use / configure.
Here is a new version (v2) of the patch:
> - rebased on latest kernel
> - fixed coding style issues
>
> Francois-Nicolas
> ---
> drivers/watchdog/iTCO_wdt.c | 50 +++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 50 insertions(+)
>
> diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c
> index 3c3fd41..cd2569a 100644
> --- a/drivers/watchdog/iTCO_wdt.c
> +++ b/drivers/watchdog/iTCO_wdt.c
> @@ -68,6 +68,8 @@
> #include <linux/io.h> /* For inb/outb/... */
> #include <linux/mfd/core.h>
> #include <linux/mfd/lpc_ich.h>
> +#include <linux/nmi.h>
> +#include <linux/acpi.h>
>
> #include "iTCO_vendor.h"
>
> @@ -127,6 +129,12 @@ module_param(turn_SMI_watchdog_clear_off, int, 0);
> MODULE_PARM_DESC(turn_SMI_watchdog_clear_off,
> "Turn off SMI clearing watchdog (depends on TCO-version)(default=1)");
>
> +#define DEFAULT_PRETIMEOUT 0
> +static bool pretimeout = DEFAULT_PRETIMEOUT;
> +module_param(pretimeout, bool, 0);
> +MODULE_PARM_DESC(pretimeout, "Enable watchdog pretimeout (default="
> + __MODULE_STRING(DEFAULT_PRETIMEOUT) ")");
> +
> /*
> * Some TCO specific functions
> */
> @@ -201,6 +209,45 @@ static int iTCO_wdt_unset_NO_REBOOT_bit(void)
> return ret; /* returns: 0 = OK, -EIO = Error */
> }
>
> +static unsigned char *tco_hid = "8086229C";
> +
Do people understand what this means ? Is that some Intel magic string ?
Does this work for all instances of iTCO watchdogs, or only for a specific
system or iTCO version ?
Rafael asked this question as well, but I don't recall seeing an answer.
I see that it maps to a PCI ID for Intel Braswell, but I have no idea
how that translates to something useful for ACPI. Is this a well defined
(and allocated) ACPI HID ? How about other chips (non-Braswell)
which are supported by this driver ?
> +static u32 iTCO_wdt_pretimeout_handler(acpi_handle gpe_device, u32 gpe,
> + void *context)
> +{
> + /* dump backtraces for all available cores */
> + trigger_all_cpu_backtrace();
> +
> + /* call panic notifiers */
> + panic("Kernel Watchdog");
> +
> + return ACPI_INTERRUPT_HANDLED;
> +}
> +
> +static acpi_status __init iTCO_wdt_register_gpe(acpi_handle handle,
> + u32 lvl, void *context, void **rv)
> +{
> + unsigned long long gpe;
> + acpi_status status;
> + union acpi_object object = { 0 };
> + struct acpi_buffer buffer = { sizeof(union acpi_object), &object };
> +
> + status = acpi_evaluate_object(handle, "_GPE", NULL, &buffer);
> + if (ACPI_FAILURE(status))
> + return status;
> +
> + if (object.type != ACPI_TYPE_INTEGER)
> + return AE_BAD_DATA;
> +
> + gpe = object.integer.value;
> + status = acpi_install_gpe_handler(NULL, gpe, ACPI_GPE_EDGE_TRIGGERED,
> + iTCO_wdt_pretimeout_handler, NULL);
Do we know for sure that _GPE is always associated with the watchdog ?
Is that because of tco_hid ?
Thanks,
Guenter
> + if (ACPI_FAILURE(status))
> + return status;
> +
> + acpi_enable_gpe(NULL, gpe);
> + return AE_OK;
> +}
> +
> static int iTCO_wdt_start(struct watchdog_device *wd_dev)
> {
> unsigned int val;
> @@ -641,6 +688,9 @@ static int __init iTCO_wdt_init_module(void)
> if (err)
> return err;
>
> + if (pretimeout)
> + acpi_get_devices(tco_hid, iTCO_wdt_register_gpe, NULL, NULL);
> +
> return 0;
> }
>
>
next prev parent reply other threads:[~2015-06-17 5:15 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-15 15:00 [PATCH] TCO watchdog pretimeout handler Francois-Nicolas Muller
2015-06-15 18:29 ` Guenter Roeck
2015-06-16 13:45 ` [PATCH v2] " Francois-Nicolas Muller
2015-06-17 5:14 ` Guenter Roeck [this message]
2015-06-17 13:34 ` [PATCH v3] " Francois-Nicolas Muller
2015-06-17 16:06 ` Andy Shevchenko
2015-06-18 12:41 ` Muller, Francois-nicolas
2015-06-18 12:41 ` Muller, Francois-nicolas
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=55810251.6070106@roeck-us.net \
--to=linux@roeck-us.net \
--cc=francois-nicolas.muller@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-watchdog@vger.kernel.org \
--cc=wim@iguana.be \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.