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 :

quoted

quoted

   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...

quoted

[    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.

-- 
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