Re: [PATCH] reboot: add reboot_panic parameter

[Andrew Morton]

On Thu, 5 Jul 2018 06:47:37 +0000 "Tian, Baofeng" <baofeng.tian@xxxxxxxxx> wrote:

> -----Original Message-----
> From: Andrew Morton [mailto:akpm@xxxxxxxxxxxxxxxxxxxx] 
> Sent: Tuesday, July 3, 2018 5:31 AM
> To: Tian, Baofeng <baofeng.tian@xxxxxxxxx>
> Cc: andrew.smirnov@xxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Zhuang, Qihua <qihua.zhuang@xxxxxxxxx>
> Subject: Re: [PATCH] reboot: add reboot_panic parameter
> 
> On Mon, 2 Jul 2018 02:20:59 +0000 "Tian, Baofeng" <baofeng.tian@xxxxxxxxx> wrote:
> 
> > This "reboot_panic" kernel cmdline parameter allow to change the 
> > reboot mode in case of panic only. It use the same format as the 
> > "reboot" parameter.
> > Example, for cf9 warm reset in case of panic: reboot_panic=p,w 
> > currently it only support cold/warm reset in case of panic.
> 
> Why should we do this?  What are the benefits, what are the usecases, etc?  
> 
> Some user-facing documentation should clear that up.  `grep -r reboot= Documentation' will direct you to the appropriate places.
> 

(top-posting repaired.  Please don't top-post)

> Hi, Morton

"Andrew" :)

> On android platform, if use adb reboot, it will automatically reboot with cold reset.
> cold reset will reset RAM and cause RAM lose data information, if we want to enable some debug features
> like pstore, and ramdump etc, warm reset is needed to keep RAM across reset
> 
> So, we add this interface to allow people to set reboot as warm to get log data across reset.
> 

OK, sounds good.  Please add this info to the changelog, add the user
documentation and resend.