Re: [PATCH 0/3 v11] add reserved e820 ranges to the kdump kernel e820 table

[Baoquan He]

On 06/08/19 at 12:06pm, Borislav Petkov wrote:
> On Sat, Jun 08, 2019 at 06:01:39PM +0800, Baoquan He wrote:
> > OK, it may be different with the case we met, if panic happened when
> > load a kdump kernel.
> > 
> > We can load with 'kexec -l' or 'kexec -p', but can't boot after triggering
> > crash or execute 'kexec -e' to do kexec jumping.
> 
> No, I load a kdump kernel properly with this command:
> 
>  kexec -s -p /boot/vmlinuz-5.2.0-rc3+ --initrd=/boot/initrd.img-5.2.0-rc3+ --command-line="maxcpus=1 root=/dev/sda5 ro debug ignore_loglevel
> log_buf_len=16M no_console_suspend net.ifnames=0 systemd.log_target=null mem_encrypt=on kvm_amd.sev=1 nr_cpus=1 irqpoll reset_devices vga=normal
> LANG=en_US.UTF-8 earlyprintk=serial cgroup_disable=memory mce=off numa=off udev.children-max=2 panic=10 rootflags=nofail acpi_no_memhotplug
> transparent_hugepage=never disable_cpu_apicid=0"
> 
> And that succeeds judging from
> 
> $ grep . /sys/kernel/kexec_*
> 
> Then I trigger a panic with
> 
> echo c > /proc/sysrq-trigger
> 
> and this is where it hangs and doesn't load the kdump kernel.

OK, I see. Then it should be the issue we have met and talked about with
Tom.
https://lkml.kernel.org/r/20190604134952.GC26891@MiWiFi-R3L-srv

You can apply Tom's patch as below. I tested it, it can make kexec
kernel succeed to boot, but failed for kdump kernel booting. The kdump
kernel can boot till the end of kernel initialization, then hang with a
call trace. I have pasted the log in the above thread. Haven't got the
reason.
http://lkml.kernel.org/r/508c2853-dc4f-70a6-6fa8-97c950dc31c6@xxxxxxx