Re: [Qemu-devel] [PATCH] vhost-user: support cross-endianess negatiation

[Felipe Franciosi]

Hello!

On 14 Jun 2017, at 18:17, Marc-André Lureau 
<address@hidden<mailto:address@hidden>> wrote:

H

On Wed, Jun 14, 2017 at 8:42 PM Felipe Franciosi 
<address@hidden<mailto:address@hidden>> wrote:

...
@@ -580,6 +581,19 @@ Master message types
       This request should be send only when VIRTIO_F_IOMMU_PLATFORM feature
       has been successfully negotiated.

+ * VHOST_USER_SET_VRING_ENDIAN
+
+      Id: 22
+      Equivalent ioctl: VHOST_SET_VRING_ENDIAN
+      Master payload: vring state description
+
+      Set the endianess of a VQ for legacy devices. Big-endian is indicated
+      with state.num set to true, and little-endian is indicated with state.num
+      set to false.
+      This request should be sent only when VHOST_USER_PROTOCOL_F_CROSS_ENDIAN
+      has been negotiated.

And it can be sent at any time? multiple times? Do we expect the backend to 
handle any endianess?

Thanks for the feedback. I tried to write the docs to the same level of detail 
of the other messages, but agree that we should start to make an effort to have 
more elaborate documentation. I'll address your questions on the spec and send 
a v2.

I also noticed the "id" above (on the doc) should be 23.

Thanks,
Felipe