Re: [PATCH v16 net-next 0/1] introduce Hyper-V VM Sockets(hv_sock)
From: Michal Kubecek
Date: Wed Jul 13 2016 - 03:30:58 EST
On Mon, Jul 11, 2016 at 02:54:59PM +0000, Dexuan Cui wrote:
> I know the kernel has already had a VM Sockets driver (AF_VSOCK) based
> on VMware VMCI (net/vmw_vsock/, drivers/misc/vmw_vmci), and KVM is
> proposing AF_VSOCK of virtio version:
> However, though Hyper-V Sockets may seem conceptually similar to
> AF_VOSCK, there are differences in the transportation layer, and IMO these
> make the direct code reusing impractical:
> 1. In AF_VSOCK, the endpoint type is: <u32 ContextID, u32 Port>, but in
> AF_HYPERV, the endpoint type is: <GUID VM_ID, GUID ServiceID>. Here GUID
> is 128-bit.
OK, this could be a problem.
> 2. AF_VSOCK supports SOCK_DGRAM, while AF_HYPERV doesn't.
> 3. AF_VSOCK supports some special sock opts, like SO_VM_SOCKETS_BUFFER_SIZE,
> SO_VM_SOCKETS_BUFFER_MIN/MAX_SIZE and SO_VM_SOCKETS_CONNECT_TIMEOUT.
> These are meaningless to AF_HYPERV.
> 4. Some AF_VSOCK's VMCI transportation ops are meanless to AF_HYPERV/VMBus,
> like .notify_recv_init
> So I think we'd better introduce a new address family: AF_HYPERV.
I don't quite understand the logic here. All these sound like "AF_VSOCK
has this feature we don't need so (rather than not using the feature) we
are not going to use AF_VSOCK". I would understand if you pointed out
features important for you that are missing in AF_VSOCK but this kind of
reasoning sounds strange to me.