On Mon, 12 Apr 2021 13:44:45 +0200, Jaroslav Kysela wrote: > > Dne 12. 04. 21 v 13:17 Takashi Iwai napsal(a): > > >> In this case, we have 31 free bits and this information can be stored there. I > >> would prefer to keep the reserved bytes for some large fields. > > > > Again, C language doesn't define the position of the bit fields. > > That's the primary problem. > > Yes and no. It seems that it's not a big C compiler implementation problem, > because other drivers are using the bitfields in the uapi structures, too. > Yes, it may need some extra care. Right, and the need for care is mostly for little merit -- that's the point. I'm not against about the bit flags at all, but pointing that the C bit fields are too error-prone for ioctl structs. > > If we really have to save the space, it's a nice workaround. But for > > other purposes, there is really little merit and more flip side by > > that. > > I see your reluctance to talk about extension of the bit field word, but > perhaps, we may be clever and define the flag word for the newly added > parameters now. The space may be used more precisely in the future with this > change. Sure, that pattern is common and recommended for bit-wise flags. thanks, Takashi
