Re: [PATCH 1/2] kdump/fadump: fix network interface name when switching from fadump to kdump

[Hari Bathini]

On Wednesday 14 September 2016 02:02 PM, Hari Bathini wrote:
> Hi Dave,
>
> On Wednesday 14 September 2016 01:22 PM, Dave Young wrote:
> > Hi, Hari
> >
> > On 09/14/16 at 12:57pm, Hari Bathini wrote:
> > > On Monday 12 September 2016 10:18 PM, Hari Bathini wrote:
> > > > On Monday 12 September 2016 10:08 PM, Hari Bathini wrote:
> > > > > Hi Dave,
> > > > >
> > > > > On Monday 12 September 2016 07:35 AM, Dave Young wrote:
> > > > > > Hi, Hari
> > > > > >
> > > > > > Thanks for sending the patches.
> > > > > >
> > > > > > The issue will not happen if we restore default initrd in patch 2/2,
> > > > > > right? So patch 1/2 is not necessary?
> > > > >
> > > > > Actually, the first reboot after switching over from fadump to kdump
> > > > > still holds the interface name with "kdump-" prefix as we haven't
> > > > > restored
> > > > > the default initrd yet. This patch intents to cover that and also,
> > > > > to restore
> > > > > the original interface name for subsequent reboots..
> > >
> > > Hi Dave,
> > >
> > > Another possible case is rebuild may not happen on switching from 
> > > fadump to
> > > kdump,
> > > if config files are not changed. I could restore as part of 
> > > start_dump() but
> > > that doesn't
> > > sound right to me. Posted v2 with this patch intact. Please review..
> >
> > I got the problem, do you have any method to know the fadump mode
> > changing?  Ideally we should check and rebuild when the mode changes.
>
> If /sys/kernel/fadump_registered node is not available and default 
> initrd is
> built with kdump module, it signifies that we switched from fadump to
> kdump. That is after a reboot though where we already have the ifname
> with "kdump-" prefix..
>
> Thanks
> Hari

Hi Dave,

How about something like this..

is_mode_switched()
{
     initrd_fadump_capable=`lsinitrd -m $DEFAULT_INITRD | grep 
^kdumpbase$ | wc -l`
     if [ !is_fadump_capable ] && [ initrd_fadump_capable ]
         return 1

return 0
}

check_rebuid()
{
...
    is_mode_switched
     if [ $? -ne 0 ]
         rebuild_initrd
...
}

This hunk added to patch 2/2 should take care of restoring default initrd on
switch. But I am worried about the ifname that kdump gets on first reboot.
Let me know if you have any reservations with patch 1/2?

Thanks
Hari
> > Thanks
> > Dave
>
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