From mboxrd@z Thu Jan  1 00:00:00 1970
From: Wen Congyang <wency@cn.fujitsu.com>
Subject: question about migration
Date: Thu, 24 Dec 2015 10:29:52 +0800
Message-ID: <567B58A0.7010201@cn.fujitsu.com>
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To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: xen devel <xen-devel@lists.xen.org>
List-Id: xen-devel@lists.xenproject.org

Hi Andrew Cooper:

I rebase the COLO codes to the newest upstream xen, and test it. I found
a problem in the test, and I can reproduce this problem via the migration.

How to reproduce:
1. xl cr -p hvm_nopv
2. xl migrate hvm_nopv 192.168.3.1

The migration successes, but the vm doesn't run in the target machine.
You can get the reason from 'xl dmesg':
(XEN) HVM2 restore: VMCE_VCPU 1
(XEN) HVM2 restore: TSC_ADJUST 0
(XEN) HVM2 restore: TSC_ADJUST 1
(d2) HVM Loader
(d2) Detected Xen v4.7-unstable
(d2) Get guest memory maps[128] failed. (-38)
(d2) *** HVMLoader bug at e820.c:39
(d2) *** HVMLoader crashed.

The reason is that:
We don't call xc_domain_set_memory_map() in the target machine.
When we create a hvm domain:
libxl__domain_build()
    libxl__build_hvm()
        libxl__arch_domain_construct_memmap()
            xc_domain_set_memory_map()

Should we migrate the guest memory from source machine to target machine?

Thanks
Wen Congyang