Re: VMCORE and kdump.conf file not found LINUX 6.12 KERNEL

[Philipp Rudo <prudo@redhat.com>]

Hi,

On Tue, 18 Feb 2025 16:48:26 +0800
Dave Young <dyoung@redhat.com> wrote:

> On Tue, 18 Feb 2025 at 14:07, Gokul Praveen <g-praveen@ti.com> wrote:
> >
> > Hi Team,
> >
> > Just a reminder.
> > It would be really great if you could help me with the following.
> >
> > Regards
> > Gokul
> >
> > On 05/02/25 17:50, Gokul Praveen wrote:  
> > > Hi Team,
> > >
> > > It would be really great,if you could help me with a couple of questions
> > > regarding kexec and kdump.
> > >
> > > I tried kdump on my SOC and it is rebooting fine . However,the VMCORE
> > > file and /etc/kdump.conf file is not found.
> > >
> > > VERSION:
> > > kexec-tools 2.0.30.
> > > kernel 6.12v
> > >
> > > STEPS FOLLOWED:
> > >
> > > 1)git clone git://git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git
> > >
> > > 2)
> > >     HOST PC:  
> > >      >cd $KEXEC_TOOLS_DIR
> > >      >./bootstrap LDFLAGS=-static ./configure --prefix=/usr/local  
> > > --host=aarch64-linux-gnu --target=aarch64-linux-gnu  
> > >      >make
> > >      >cp $KEXEC_TOOLS_DIR/build/sbin/kexec /media/$USER/rootfs/usr/sbin  
> > > (To copy the kexec binary to the rootfs filesystem of the target board)
> > >
> > >     TARGET BOARD:  
> > >      >Booted upto linux
> > >      >cmdline="crashkernel=128M console=ttyS2,115200n8  
> > > root=/dev/mmcblk0p2 rw rootfste=ext4 rootwait" (/dev/mmcblk0p2 refers to
> > > EMMC)  
> > >      > /kexec -p /Image --command-line="$cmdline"  
> > > --dtb=/k3-j721e-common-proc-board.dtb

The kdump kernel only presents the dump via /proc/vmcore but doesn't
write it to disk. That is done by user space contained in the initrd.
So for it to work you also have to provide an initrd that mounts the
target disk and writes the dump to it. But, as Dave already pointed
out, the creation of initrds is highly distro specific.

Thanks
Philipp

> > >      > echo c > /proc/sysrq-trigger  
> 
> Hi,
> 
> This looks more like a distribution related issue, I suggest you ask
> distribution developers to help.
> 
> Thanks
> Dave
> 
>