* [PATCH] vsock.7: add VMADDR_CID_LOCAL description
@ 2020-02-11 10:25 Stefano Garzarella
2020-02-13 9:17 ` Stefan Hajnoczi
0 siblings, 1 reply; 3+ messages in thread
From: Stefano Garzarella @ 2020-02-11 10:25 UTC (permalink / raw)
To: mtk.manpages
Cc: Stefan Hajnoczi, netdev, linux-man, Dexuan Cui, Jorgen Hansen
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.
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
man7/vsock.7 | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/man7/vsock.7 b/man7/vsock.7
index c5ffcf07d..d7dc37dcc 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) can be used to address itself. In this case all packets are redirected
+to the same host that generated them. Useful for testing and 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 +232,8 @@ 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.
.SH SEE ALSO
.BR bind (2),
.BR connect (2),
--
2.24.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] vsock.7: add VMADDR_CID_LOCAL description
2020-02-11 10:25 [PATCH] vsock.7: add VMADDR_CID_LOCAL description Stefano Garzarella
@ 2020-02-13 9:17 ` Stefan Hajnoczi
2020-02-13 9:44 ` Stefano Garzarella
0 siblings, 1 reply; 3+ messages in thread
From: Stefan Hajnoczi @ 2020-02-13 9:17 UTC (permalink / raw)
To: Stefano Garzarella
Cc: mtk.manpages, netdev, linux-man, Dexuan Cui, Jorgen Hansen
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On Tue, Feb 11, 2020 at 11:25:32AM +0100, Stefano Garzarella wrote:
Do you want to mention that loopback works in the guest and on the host
since Linux vX.Y and before that it only worked inside the guest?
> @@ -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) can be used to address itself. In this case all packets are redirected
> +to the same host that generated them. Useful for testing and debugging.
This can be rephrased more naturally:
.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.
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] vsock.7: add VMADDR_CID_LOCAL description
2020-02-13 9:17 ` Stefan Hajnoczi
@ 2020-02-13 9:44 ` Stefano Garzarella
0 siblings, 0 replies; 3+ messages in thread
From: Stefano Garzarella @ 2020-02-13 9:44 UTC (permalink / raw)
To: Stefan Hajnoczi
Cc: mtk.manpages, netdev, linux-man, Dexuan Cui, Jorgen Hansen
On Thu, Feb 13, 2020 at 09:17:48AM +0000, Stefan Hajnoczi wrote:
> On Tue, Feb 11, 2020 at 11:25:32AM +0100, Stefano Garzarella wrote:
>
> Do you want to mention that loopback works in the guest and on the host
> since Linux vX.Y and before that it only worked inside the guest?
I didn't mention it, because it was only supported by some transports
(vmci, virtio), but it makes sense to say it, I'll add.
>
> > @@ -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) can be used to address itself. In this case all packets are redirected
> > +to the same host that generated them. Useful for testing and debugging.
>
> This can be rephrased more naturally:
>
> .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.
Sure, it is better, I'll fix.
Thanks,
Stefano
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-02-13 9:17 ` Stefan Hajnoczi
2020-02-13 9:44 ` Stefano Garzarella
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