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To:     <xieyongji@bytedance.com>
References: <20210831103634.33-1-xieyongji@bytedance.com>
Subject: Re: [PATCH v13 00/13] Introduce VDUSE - vDPA Device in Userspace
CC:     "Fangyi (Eric)" <eric.fangyi@huawei.com>, <yebiaoxiang@huawei.com>,
        <x86@kernel.org>, <kvm@vger.kernel.org>,
        <linux-fsdevel@vger.kernel.org>, <linux-kernel@vger.kernel.org>
From:   Liuxiangdong <liuxiangdong5@huawei.com>
Message-ID: <6163E8A1.8080901@huawei.com>
Date:   Mon, 11 Oct 2021 15:32:49 +0800
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Hi, Yongji.

I tried vduse with null-blk:

   $ qemu-storage-daemon \
       --chardev socket,id=charmonitor,path=/tmp/qmp.sock,server,nowait \
       --monitor chardev=charmonitor \
       --blockdev 
driver=host_device,cache.direct=on,aio=native,filename=/dev/nullb0,node-name=disk0 
\
       --export 
type=vduse-blk,id=test,node-name=disk0,writable=on,name=vduse-null,num-queues=16,queue-size=128

The qemu-storage-daemon is yours 
(https://github.com/bytedance/qemu/tree/vduse)

And then, how can we use this vduse-null (dev/vduse/vduse-null) in vm(QEMU)?

Because qemu-storage-daemon open this vduse-null in vduse_dev_init(), 
all the operations which open this dev
will report "failed to open '/dev/vduse/vduse-null': Device or resource 
busy".

Or something I understood wrong?

Thanks!
Xiangdong Liu