Messages in this thread | | | Date | Thu, 05 Jul 2012 08:45:56 +0200 | From | Paolo Bonzini <> | Subject | Re: [PATCH] virtio-blk: allow toggling host cache between writeback and writethrough |
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Il 04/07/2012 23:30, Michael S. Tsirkin ha scritto: >>>>>> +static int virtblk_get_cache_mode(struct virtio_device *vdev) >>>>> >>>>> Why are you converting u8 to int here? >>>> >>>> The fact that it is a u8 is really an internal detail. Perhaps the bug >>>> is using u8 in the callers. >>> >>> Make it bool then? >>> >>> You are using u8 in the config. So you could get any value >>> besides 0 and 1, and you interpret that as 1. >>> Is 1 always a safe value? If not maybe it's better to set >>> to a safe value if it is not 0 or 1, that is we don't know how to interpret it. >> >> That would be a host bug; the spec only gives meaning to 0 and 1. > > Yes but if the other side does not validate values implementations > *will* have bugs. Why not declare bits 1-7 reserved?
Ok, that would be a different change. I thought about it yesterday, but it seemed like a useless complication. It's not like we have been adding configuration fields every other week. :)
But I can certainly prepare patches to both virtio-blk and the spec for that if you prefer.
Paolo
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