Re: [PATCH v2] watchdog/hpwdt: Refine hpwdt message for UV platform

[Steve Wahl]

On Wed, Mar 18, 2026 at 10:42:09AM -0700, Guenter Roeck wrote:
> On 3/18/26 08:50, Steve Wahl wrote:
> > The watchdog hardware the hpwdt driver uses was added to the UV
> > platform for UV_5, but the logging mentioned by this driver was not
> > added to the BIOS.  When the watchdog fires, the printed message had
> > the administrators and developers looking for non-existent log files,
> > and confused about whether a watchdog actually tripped.
> > 
> > Change the message that prints on UV platforms so it doesn't send the
> > user looking for non-existent logs.
> > 
> > To aid in any future debugging, include all 8 bits of the NMISTAT
> > register in the output, not just the two bits being used to determine
> > this was "mynmi".  And provide names to the bits in NMISTAT so the
> > code is easier to understand.
> > 
> > Signed-off-by: Steve Wahl <steve.wahl@xxxxxxx>
> 
> Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>

Question: With Guenter's review, will this automatically follow some
path into the kernel tree, or do I need to call more attention to it?

Thanks,

--> Steve Wahl, HPE

> > ---
> > 
> > v1 disucsion:
> > https://lore.kernel.org/all/20260316214530.104344-1-steve.wahl@xxxxxxx
> > 
> > v2: Fix subject line; remove hpwdt_my_nmi function, and inline what it
> > formerly did, reducing complexity. This addresses comments from
> > Guenter Roeck.
> > 
> >   drivers/watchdog/hpwdt.c | 22 +++++++++++++++-------
> >   1 file changed, 15 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/watchdog/hpwdt.c b/drivers/watchdog/hpwdt.c
> > index ae30e394d176..ba08189937ec 100644
> > --- a/drivers/watchdog/hpwdt.c
> > +++ b/drivers/watchdog/hpwdt.c
> > @@ -22,6 +22,7 @@
> >   #include <linux/watchdog.h>
> >   #ifdef CONFIG_HPWDT_NMI_DECODING
> >   #include <asm/nmi.h>
> > +#include <asm/uv/uv.h>
> >   #endif
> >   #include <linux/crash_dump.h>
> > @@ -158,24 +159,31 @@ static int hpwdt_set_pretimeout(struct watchdog_device *wdd, unsigned int req)
> >   	return 0;
> >   }
> > -static int hpwdt_my_nmi(void)
> > -{
> > -	return ioread8(hpwdt_nmistat) & 0x6;
> > -}
> > +#define NMISTAT_EASR	BIT(0)
> > +#define NMISTAT_EWDOG	BIT(1)
> > +#define NMISTAT_RTRAP	BIT(2)
> > +#define NMISTAT_DBELL	BIT(3)
> > +#define NMISTAT_EMSWDG	BIT(4)
> > +#define NMISTAT_GPI	BIT(5)
> > +#define NMISTAT_NMIOUT	BIT(7)
> >   /*
> >    *	NMI Handler
> >    */
> >   static int hpwdt_pretimeout(unsigned int ulReason, struct pt_regs *regs)
> >   {
> > -	unsigned int mynmi = hpwdt_my_nmi();
> > -	static char panic_msg[] =
> > +	u8 nmistat = ioread8(hpwdt_nmistat);
> > +	bool mynmi = (nmistat & (NMISTAT_EWDOG | NMISTAT_RTRAP)) != 0;
> > +	static char panic_msg_default[] =
> >   		"00: An NMI occurred. Depending on your system the reason "
> >   		"for the NMI is logged in any one of the following resources:\n"
> >   		"1. Integrated Management Log (IML)\n"
> >   		"2. OA Syslog\n"
> >   		"3. OA Forward Progress Log\n"
> >   		"4. iLO Event Log";
> > +	static char panic_msg_uv[] =
> > +		"00: A watchdog NMI occurred.";
> > +	char *panic_msg = is_uv_system() ? panic_msg_uv : panic_msg_default;
> >   	if (ulReason == NMI_UNKNOWN && !mynmi)
> >   		return NMI_DONE;
> > @@ -189,7 +197,7 @@ static int hpwdt_pretimeout(unsigned int ulReason, struct pt_regs *regs)
> >   		hpwdt_ping_ticks(SECS_TO_TICKS(val));
> >   	}
> > -	hex_byte_pack(panic_msg, mynmi);
> > +	hex_byte_pack(panic_msg, nmistat);
> >   	nmi_panic(regs, panic_msg);
> >   	return NMI_HANDLED;
> 

-- 
Steve Wahl, Hewlett Packard Enterprise