Re: DAX can not work on virtual nvdimm device

Xiao Guangrong
2016-08-31T08:44:47Z

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!