Re: [Qemu-devel] [PATCH 1/2] vhost: enable any layout feature

[Stephen Hemminger]

On Tue, 27 Sep 2016 11:11:58 +0800
Yuanhan Liu <address@hidden> wrote:

> On Mon, Sep 26, 2016 at 10:24:55PM +0300, Michael S. Tsirkin wrote:
> > On Mon, Sep 26, 2016 at 11:01:58AM -0700, Stephen Hemminger wrote:  
> > > I assume that if using Version 1 that the bit will be ignored  
> 
> Yes, but I will just quote what you just said: what if the guest
> virtio device is a legacy device? I also gave my reasons in another
> email why I consistently set this flag:
> 
>   - we have to return all features we support to the guest.
>   
>     We don't know the guest is a modern or legacy device. That means
>     we should claim we support both: VERSION_1 and ANY_LAYOUT.
>   
>     Assume guest is a legacy device and we just set VERSION_1 (the current
>     case), ANY_LAYOUT will never be negotiated.
>   
>   - I'm following the way Linux kernel takes: it also set both features.

Agreed, just do what the Linux kernel does.