Messages in this thread | | | Date | Tue, 16 Jun 2015 22:14:57 -0700 | From | Guenter Roeck <> | Subject | Re: [PATCH v2] TCO watchdog pretimeout handler |
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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; > } > >
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