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

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Message-ID: <20190608100623.GA9138@zn.tnic>
Date:   Sat, 8 Jun 2019 12:06:23 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Baoquan He <bhe@...hat.com>
Cc:     lijiang <lijiang@...hat.com>, linux-kernel@...r.kernel.org,
        kexec@...ts.infradead.org, tglx@...utronix.de, mingo@...hat.com,
        akpm@...ux-foundation.org, dave.hansen@...ux.intel.com,
        luto@...nel.org, peterz@...radead.org, x86@...nel.org,
        hpa@...or.com, dyoung@...hat.com, Thomas.Lendacky@....com
Subject: Re: [PATCH 0/3 v11] add reserved e820 ranges to the kdump kernel
 e820 table

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.

-- 
Regards/Gruss,
    Boris.

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