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[79.27.4.209]) by smtp.gmail.com with ESMTPSA id b13sm1924870wrq.48.2020.02.17.09.31.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 Feb 2020 09:31:23 -0800 (PST) From: Stefano Garzarella To: mtk.manpages@gmail.com Cc: linux-man@vger.kernel.org, Dexuan Cui , Stefan Hajnoczi , Jorgen Hansen , netdev@vger.kernel.org Subject: [PATCH v3] vsock.7: add VMADDR_CID_LOCAL description Date: Mon, 17 Feb 2020 18:31:21 +0100 Message-Id: <20200217173121.159132-1-sgarzare@redhat.com> X-Mailer: git-send-email 2.24.1 MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Linux 5.6 added the new well-known VMADDR_CID_LOCAL for local communication. This patch explains how to use it and remove the legacy VMADDR_CID_RESERVED no longer available. Reviewed-by: Jorgen Hansen Signed-off-by: Stefano Garzarella --- v3: * rephrased "Previous versions" part [Jorgen] v2: * rephrased "Local communication" description [Stefan] * added a mention of previous versions that supported loopback only in the guest [Stefan] --- man7/vsock.7 | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) diff --git a/man7/vsock.7 b/man7/vsock.7 index c5ffcf07d..219e3505f 100644 --- a/man7/vsock.7 +++ b/man7/vsock.7 @@ -127,8 +127,8 @@ There are several special addresses: means any address for binding; .B VMADDR_CID_HYPERVISOR (0) is reserved for services built into the hypervisor; -.B VMADDR_CID_RESERVED -(1) must not be used; +.B VMADDR_CID_LOCAL +(1) is the well-known address for local communication (loopback); .B VMADDR_CID_HOST (2) is the well-known address of the host. @@ -164,6 +164,16 @@ Consider using .B VMADDR_CID_ANY when binding instead of getting the local CID with .BR IOCTL_VM_SOCKETS_GET_LOCAL_CID . +.SS Local communication +The +.B VMADDR_CID_LOCAL +(1) directs packets to the same host that generated them. This is useful +for testing applications on a single host and for debugging. +.PP +The local CID obtained with +.BR IOCTL_VM_SOCKETS_GET_LOCAL_CID +can be used for the same purpose, but it is preferable to use +.B VMADDR_CID_LOCAL . .SH ERRORS .TP .B EACCES @@ -222,6 +232,11 @@ are valid. Support for VMware (VMCI) has been available since Linux 3.9. KVM (virtio) is supported since Linux 4.8. Hyper-V is supported since Linux 4.14. +.PP +VMADDR_CID_LOCAL is supported since Linux 5.6. +Local communication in the guest and on the host is available since Linux 5.6. +Previous versions only supported local communication within a guest +(not on the host), and only with some transports (VMCI and virtio). .SH SEE ALSO .BR bind (2), .BR connect (2),