From: Juergen Gross <jgross@suse.com>
To: xen-devel@lists.xenproject.org
Cc: Juergen Gross <jgross@suse.com>,
ian.jackson@eu.citrix.com, jbeulich@suse.com,
stefano.stabellini@eu.citrix.com
Subject: [PATCH v2] docs: add misc/qemu-backends.txt
Date: Mon, 11 Apr 2016 15:04:09 +0200 [thread overview]
Message-ID: <1460379849-27184-1-git-send-email-jgross@suse.com> (raw)
Document the interface between qemu and libxl regarding backends
supported by qemu.
Signed-off-by: Juergen Gross <jgross@suse.com>
---
v2: - replace variable Xenstore path parts (<xyz>) with bash-like syntax
($XYZ) as requested by Konrad Wilk
- add remark about de-privileged qemu as requested by Stefano
Stabellini
- add comma as suggested by Andrew Cooper
---
docs/misc/qemu-backends.txt | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
create mode 100644 docs/misc/qemu-backends.txt
diff --git a/docs/misc/qemu-backends.txt b/docs/misc/qemu-backends.txt
new file mode 100644
index 0000000..b8e1799
--- /dev/null
+++ b/docs/misc/qemu-backends.txt
@@ -0,0 +1,21 @@
+In order to know whether qemu supports a specific backend type libxl
+needs a way to obtain this information.
+
+As each qemu instance owns a path (named $QEMU from now on) in
+Xenstore, the backend information is presented there. $QEMU is built
+from the domain id where the qemu instance is running $BACKEND_DOM,
+and the domain id of the target domain of the qemu process $DOMID:
+
+$QEMU = /local/domain/$BACKEND_DOM/device-model/$DOMID
+
+Before signalling qemu is running by writing "running" to $QEMU/state
+qemu will create a Xenstore node for each supported backend under
+$QEMU/backends with the backend type as name (e.g. $QEMU/backends/qdisk
+for the qdisk backend). In case qemu is running de-privileged (not as
+user root) the backend nodes must be written before qemu is dropping
+privileges.
+
+libxl can assume a backend of a specific type $TYPE is supported if:
+- $QEMU/backends/$TYPE is existing in Xenstore
+- or $QEMU/backends is not existing and $TYPE is one of:
+ "console", "vkbd", "vfb", "qdisk", "qnic"
--
2.6.6
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel
next reply other threads:[~2016-04-11 13:04 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-11 13:04 Juergen Gross [this message]
2016-04-11 13:38 ` [PATCH v2] docs: add misc/qemu-backends.txt Konrad Rzeszutek Wilk
2016-04-11 18:21 ` Stefano Stabellini
2016-04-12 14:03 ` Wei Liu
2016-04-20 14:02 ` Wei Liu
2016-04-20 18:07 ` Wei Liu
2016-04-20 13:54 ` Juergen Gross
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=1460379849-27184-1-git-send-email-jgross@suse.com \
--to=jgross@suse.com \
--cc=ian.jackson@eu.citrix.com \
--cc=jbeulich@suse.com \
--cc=stefano.stabellini@eu.citrix.com \
--cc=xen-devel@lists.xenproject.org \
/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).