Messages in this thread |  | | Subject | Re: [PATCH net-next v6 06/15] ethtool: netlink bitset handling | From | Johannes Berg <> | Date | Thu, 04 Jul 2019 14:03:02 +0200 |
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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
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