Re: [PATCH 1/2] vhost: add ioctl to query nregions upper limit

Paolo Bonzini
2015-07-29T15:01:48Z

On 29/07/2015 16:56, Michael S. Tsirkin wrote:
>>>> > > > Also, document our contract with legacy userspace: when running on an
>>>> > > > old kernel, you get -1 and you can assume at least 64 slots. Since 0
>>>> > > > value's left unused, let's make that mean that the current userspace
>>>> > > > behaviour (trial and error) is required, just in case we want it back.
>>> > >
>>> > > What's wrong with reading the module parameter value? It's there in
>>> > > sysfs ...
>> > for most cases it would work but distro doesn't have to mount
>> > sysfs under /sys
> If it wants to rewrite all userspace, sure it doesn't.

I agree, on the other hand it doesn't seem far fetched to have a per-fd
maximum in the future. So I think this patch is more future-proof.

Paolo