On Thu, 2019-07-04 at 13:52 +0200, Michal Kubecek wrote: > > There is still the question if it it should be implemented as a nested > attribute which could look like the current compact form without the > "list" flag (if there is no mask, it's a list). Or an unstructured data > block consisting of u32 bit length
You wouldn't really need the length, since the attribute has a length already :-) And then, if you just concatenate the value and mask, the existing NLA_BITFIELD32 becomes a special case. > and one or two bitmaps of > corresponding length. I would prefer the nested attribute, netlink was > designed to represent structured data, passing structures as binary goes > against the design (just looked at VFINFO in rtnetlink few days ago, > it's awful, IMHO). Yeah, I dunno. On the one hand I completely agree, on the other hand NLA_BITFIELD32 already goes the other way, and is there now... > Either way, I would still prefer to have bitmaps represented as an array > of 32-bit blocks in host byte order. This would be easy to handle in > kernel both in places where we have u32 based bitmaps and unsigned long > based ones. Other options seem less appealing: > > - u8 based: only complicates processing > - u64 based: have to care about alignment > - unsigned long based: alignment and also problems with 64-bit kernel > vs. 32-bit userspace Agree with this. johannes
