From mboxrd@z Thu Jan  1 00:00:00 1970
From: linux@armlinux.org.uk (Russell King - ARM Linux)
Date: Wed, 16 May 2018 11:42:36 +0100
Subject: issue with kexec/kdump on imx6ull
In-Reply-To: <20180516103120.GA17813@arthur-bzh>
References: <20180320100427.GA21933@arthur-bzh>
 <20180320104302.GG2743@n2100.armlinux.org.uk>
 <20180320150723.GH2743@n2100.armlinux.org.uk>
 <20180320171608.GB32282@arthur-bzh>
 <20180320191259.GI2743@n2100.armlinux.org.uk>
 <20180321132548.GA32618@arthur-bzh>
 <20180329205413.GG16141@n2100.armlinux.org.uk>
 <20180409135852.GA22168@arthur-bzh>
 <20180409143123.GA4251@n2100.armlinux.org.uk>
 <20180516103120.GA17813@arthur-bzh>
Message-ID: <20180516104236.GI16141@n2100.armlinux.org.uk>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Wed, May 16, 2018 at 12:31:20PM +0200, Arthur LAMBERT wrote:
> Le Monday 09 Apr 2018 ? 15:31:23 (+0100), Russell King - ARM Linux a ?crit :
> > 
> > >    kernel command line: "console=ttymxc0,115200 root=/dev/mmcblk1p2 rootwait rw earlyprintk maxcpus=1 reset_devices elfcorehdr=0x9b100000 mem=50176K"
> > 
> > This is the command line which the target kernel should boot with, but...
> > 
> > > [    0.000000] Kernel command line: console=ttymxc0,115200 root=/dev/mmcblk1p2 rootwait rw crashkernel=50M
> > 
> > it appears that it hasn't, so something is still wrong.  Without the
> > right command line, you won't get the vmcore.
> 
> Sorry for my very late answer Russell.
> 
> We can see that kexec is able to build the correct command line but instead of booting with this kernel
> command line. Kexec boot the target kernel with default kernel command line.
> 
> I am currently forcing kernel command line on my target kernel :
> 
> CONFIG_CMDLINE="console=ttymxc0,115200 root=/dev/mmcblk1p2 rootwait rw earlyprintk crashkernel=50M"
> # CONFIG_CMDLINE_FROM_BOOTLOADER is not set
> # CONFIG_CMDLINE_EXTEND is not set
> CONFIG_CMDLINE_FORCE=y

I guess it's taken quite a while to track this down.

I wonder if we should encode that into the zImage, and have kexec print
a friendly error or warning message suggesting the kernel be more
appropriately configured.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 8.8Mbps down 630kbps up
According to speedtest.net: 8.21Mbps down 510kbps up