From mboxrd@z Thu Jan  1 00:00:00 1970
From: Xiao Guangrong <guangrong.xiao-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Subject: Re: DAX can not work on virtual nvdimm device
Date: Wed, 31 Aug 2016 16:44:47 +0800
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On 08/31/2016 01:09 AM, Dan Williams wrote:

>
> Can you post your exact reproduction steps?  This test is not failing for me.
>

Sure.

1. make the guest kernel based on your tree, the top commit is
    10d7902fa0e82b (dax: unmap/truncate on device shutdown) and
    the config file can be found in this thread.

2. add guest kernel command line: memmap=6G!10G

3: start the guest:
    x86_64-softmmu/qemu-system-x86_64 -machine pc,nvdimm --enable-kvm \
    -smp 16 -m 32G,maxmem=100G,slots=100 /other/VMs/centos6.img -monitor stdio

4: in guest:
    mkfs.ext4 /dev/pmem0
    mount -o dax /dev/pmem0  /mnt/pmem/
    echo > /mnt/pmem/xxx
    ./mmap /mnt/pmem/xxx
    ./read /mnt/pmem/xxx

   The source code of mmap and read has been attached in this mail.

   Hopefully, you can detect the error triggered by read test.

Thanks!