Re: Does dracut need start watchdog?

[Harald Hoyer <harald-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

On 12/10/2013 09:21 AM, Baoquan He wrote:
> On 08/09/2013 03:20 PM, Harald Hoyer wrote:
>> On 08/05/2013 12:19 PM, Baoquan He wrote:
>>> Hi Harald,
>>>
>>> Since some drivers do the soft kicking. That is if BIOS has enabled
>>> watchdog, then kernel driver kicks the hardware till user space watchdog
>>> daemon comes along. This can help sove the problem in kdump which kdump
>>> kernel reboot before vmcore saving is finished. That problem is
>>> triggered because watchdog started in 1st kernel and timeout because of
>>> stopping being kicked.
>>>
>>> I noticed in 04watchdog the watchdog.sh will start watchdog if
>>> /dev/watchdog exists. I am just wondering if it's needed to start
>>> watchdog by accessing /dev/watchdog. If starting watchdog is not needed,
>>> I want to make some code change of watchdog.sh.
>>>
>>> What's your suggestion?
>>>
>>> Baoquan
>>> Thanks a lot
>>
>> Basically the 04watchdog module was used only in the testsuite. You might
>> consider to use the systemd watchdog feature instead.
>>
>> http://0pointer.de/blog/projects/watchdog.html
>>
>> or, if 0pointer is down again:
>>
>> http://webcache.googleusercontent.com/search?q=cache:jYfJU_fFZy8J:0pointer.de/blog/projects/watchdog.html
> 
> Hi,
> 
> I tried your suggestion, systemd can't help.
> 
> In /etc/systemd/system.conf, there are 2 options to control watchdog,
> however it need watchdog hardware to be present. That means watchdog
> driver need be loaded during startup.
> 
> Baoquan
> Thanks

Why can't systemd help?

dracut also uses the hardware watchdog. There is even a software watchdog device
driver (softdog).

Just load the module and systemd should start to make use of "/dev/watchdog".
With udevd in the initramfs, module loading should happen automatically, you
just have to add the watchdog modules to the initramfs.

$ echo; echo -n "instmods"; modinfo char-major-10-130 | while read a b; do [[ $a
== filename: ]] && (b=${b##*/}; echo -n " ${b%.ko}");done;echo

instmods pcwd_pci wdt_pci pcwd_usb alim1535_wdt alim7101_wdt sp5100_tco
sbc_fitpc2_wdt ib700wdt ibmasr i6300esb ie6xx_wdt iTCO_wdt it8712f_wdt it87_wdt
hpwdt nv_tco sch311x_wdt w83627hf_wdt w83697hf_wdt w83697ug_wdt w83877f_wdt
w83977f_wdt machzwd xen_wdt softdog