From: Paolo Bonzini <pbonzini@redhat.com>
To: Yang Zhong <yang.zhong@intel.com>
Cc: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
Stefan Hajnoczi <stefanha@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [Qemu-devel] The WCE issue in guest when i enable WCE in Qemu side.
Date: Wed, 24 Jul 2019 10:57:30 +0200 [thread overview]
Message-ID: <c158d398-8049-7e9c-d3be-573ff5b032d3@redhat.com> (raw)
In-Reply-To: <20190724065513.GA3369@yangzhon-Virtual>
On 24/07/19 08:55, Yang Zhong wrote:
>
> The SPDK code i am using is latest version, So, i feel we should
> enable WCE feature in SPDK side by default. thanks for your help!
Note that enabling the CONFIG_WCE feature has some consequences.
According to the spec:
- if the VIRTIO_BLK_F_CONFIG_WCE feature was negotiated and the
writeback field in configuration space was 0 all the time between the
submission of the write and its completion, the device MUST ensure that
stable writes are committed to persistent storage before reporting
completion of the write. This means using FUA writes or something like that
- the device MUST offset VIRTIO_BLK_F_FLUSH if they offer
VIRTIO_BLK_F_CONFIG_WCE
- if VIRTIO_BLK_F_CONFIG_WCE is negotiated but VIRTIO_BLK_F_FLUSH is
not, the device MUST initialize writeback to 0
Paolo
next prev parent reply other threads:[~2019-07-24 8:59 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-23 12:17 [Qemu-devel] The WCE issue in guest when i enable WCE in Qemu side Zhong, Yang
2019-07-23 15:32 ` Paolo Bonzini
2019-07-24 6:55 ` Yang Zhong
2019-07-24 8:57 ` Paolo Bonzini [this message]
2019-07-24 12:47 ` Yang Zhong
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=c158d398-8049-7e9c-d3be-573ff5b032d3@redhat.com \
--to=pbonzini@redhat.com \
--cc=mst@redhat.com \
--cc=qemu-devel@nongnu.org \
--cc=stefanha@redhat.com \
--cc=yang.zhong@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).