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gerrit-public.fairphone.software / kernel / msm-4.19 / 6dc06c08bef1c746ff8da33dab677cfbacdcad32 / . / Documentation / watchdog / hpwdt.txt
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Brian Boylston0215efc2016-05-25 11:20:15 -0500[diff] [blame]1Last reviewed: 05/20/2016
Thomas Mingarelli47bece82009-06-04 19:50:45 +0000[diff] [blame]2
Nigel Croxon84df0822016-04-06 14:40:05 -0400[diff] [blame]3 HPE iLO NMI Watchdog Driver
4 NMI sourcing for iLO based ProLiant Servers
Thomas Mingarelli47bece82009-06-04 19:50:45 +0000[diff] [blame]5 Documentation and Driver by
Brian Boylston0215efc2016-05-25 11:20:15 -0500[diff] [blame]6 Thomas Mingarelli
Thomas Mingarelli47bece82009-06-04 19:50:45 +0000[diff] [blame]7
Nigel Croxon84df0822016-04-06 14:40:05 -0400[diff] [blame]8 The HPE iLO NMI Watchdog driver is a kernel module that provides basic
Thomas Mingarelli47bece82009-06-04 19:50:45 +0000[diff] [blame]9 watchdog functionality and the added benefit of NMI sourcing. Both the
10 watchdog functionality and the NMI sourcing capability need to be enabled
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300[diff] [blame]11 by the user. Remember that the two modes are not dependent on one another.
Thomas Mingarelli47bece82009-06-04 19:50:45 +0000[diff] [blame]12 A user can have the NMI sourcing without the watchdog timer and vice-versa.
Nigel Croxon84df0822016-04-06 14:40:05 -0400[diff] [blame]13 All references to iLO in this document imply it also works on iLO2 and all
14 subsequent generations.
Thomas Mingarelli47bece82009-06-04 19:50:45 +0000[diff] [blame]15
16 Watchdog functionality is enabled like any other common watchdog driver. That
17 is, an application needs to be started that kicks off the watchdog timer. A
18 basic application exists in the Documentation/watchdog/src directory called
19 watchdog-test.c. Simply compile the C file and kick it off. If the system
Nigel Croxon84df0822016-04-06 14:40:05 -0400[diff] [blame]20 gets into a bad state and hangs, the HPE ProLiant iLO timer register will
Thomas Mingarelli47bece82009-06-04 19:50:45 +0000[diff] [blame]21 not be updated in a timely fashion and a hardware system reset (also known as
22 an Automatic Server Recovery (ASR)) event will occur.
23
Nigel Croxon84df0822016-04-06 14:40:05 -0400[diff] [blame]24 The hpwdt driver also has three (3) module parameters. They are the following:
Thomas Mingarelli47bece82009-06-04 19:50:45 +0000[diff] [blame]25
Nigel Croxon84df0822016-04-06 14:40:05 -0400[diff] [blame]26 soft_margin - allows the user to set the watchdog timer value.
27 Default value is 30 seconds.
28 allow_kdump - allows the user to save off a kernel dump image after an NMI.
29 Default value is 1/ON
Thomas Mingarelli47bece82009-06-04 19:50:45 +0000[diff] [blame]30 nowayout - basic watchdog parameter that does not allow the timer to
31 be restarted or an impending ASR to be escaped.
Nigel Croxon84df0822016-04-06 14:40:05 -0400[diff] [blame]32 Default value is set when compiling the kernel. If it is set
33 to "Y", then there is no way of disabling the watchdog once
34 it has been started.
Thomas Mingarelli47bece82009-06-04 19:50:45 +0000[diff] [blame]35
36 NOTE: More information about watchdog drivers in general, including the ioctl
37 interface to /dev/watchdog can be found in
38 Documentation/watchdog/watchdog-api.txt and Documentation/IPMI.txt.
39
Tom Mingarelli44df7532009-06-18 23:28:57 +0000[diff] [blame]40 The NMI sourcing capability is disabled by default due to the inability to
Thomas Mingarelli47bece82009-06-04 19:50:45 +0000[diff] [blame]41 distinguish between "NMI Watchdog Ticks" and "HW generated NMI events" in the
42 Linux kernel. What this means is that the hpwdt nmi handler code is called
43 each time the NMI signal fires off. This could amount to several thousands of
44 NMIs in a matter of seconds. If a user sees the Linux kernel's "dazed and
45 confused" message in the logs or if the system gets into a hung state, then
Nigel Croxon84df0822016-04-06 14:40:05 -0400[diff] [blame]46 the hpwdt driver can be reloaded.
Thomas Mingarelli47bece82009-06-04 19:50:45 +0000[diff] [blame]47
48 1. If the kernel has not been booted with nmi_watchdog turned off then
Nigel Croxon84df0822016-04-06 14:40:05 -0400[diff] [blame]49 edit and place the nmi_watchdog=0 at the end of the currently booting
50 kernel line. Depending on your Linux distribution and platform setup:
51 For non-UEFI systems
52 /boot/grub/grub.conf or
53 /boot/grub/menu.lst
54 For UEFI systems
55 /boot/efi/EFI/distroname/grub.conf or
56 /boot/efi/efi/distroname/elilo.conf
Thomas Mingarelli47bece82009-06-04 19:50:45 +0000[diff] [blame]57 2. reboot the sever
Nigel Croxon84df0822016-04-06 14:40:05 -0400[diff] [blame]58 3. Once the system comes up perform a modprobe -r hpwdt
59 4. modprobe /lib/modules/`uname -r`/kernel/drivers/watchdog/hpwdt.ko
Thomas Mingarelli47bece82009-06-04 19:50:45 +0000[diff] [blame]60
61 Now, the hpwdt can successfully receive and source the NMI and provide a log
Nigel Croxon84df0822016-04-06 14:40:05 -0400[diff] [blame]62 message that details the reason for the NMI (as determined by the HPE BIOS).
Thomas Mingarelli47bece82009-06-04 19:50:45 +0000[diff] [blame]63
Nigel Croxon84df0822016-04-06 14:40:05 -0400[diff] [blame]64 Below is a list of NMIs the HPE BIOS understands along with the associated
Thomas Mingarelli47bece82009-06-04 19:50:45 +0000[diff] [blame]65 code (reason):
66
67 No source found 00h
68
69 Uncorrectable Memory Error 01h
70
71 ASR NMI 1Bh
72
73 PCI Parity Error 20h
74
75 NMI Button Press 27h
76
77 SB_BUS_NMI 28h
78
79 ILO Doorbell NMI 29h
80
81 ILO IOP NMI 2Ah
82
83 ILO Watchdog NMI 2Bh
84
85 Proc Throt NMI 2Ch
86
87 Front Side Bus NMI 2Dh
88
89 PCI Express Error 2Fh
90
91 DMA controller NMI 30h
92
93 Hypertransport/CSI Error 31h
94
95
96
97 -- Tom Mingarelli