On 10/13/2009 04:53 PM, Roland McGrath wrote: >> My only concern is the support of 64-bit clone flags on 32-bit architectures. > > Oy. I didn't realize there was serious consideration of having more than > 32 flags. IMHO it would be a bad choice, since they could only be used via > clone3. Having high-bit flags work in clone on 64-bit machines but not on > 32-bit machines just seems like a wrongly confusing way for things to be. > If any high-bits flags are constrained even on 64-bit machines to uses in > clone3 calls for sanity purposes, then it seems questionable IMHO to have > them be more flags in the same u64 at all. > > Since all new features will be via this struct, various new kinds of things > could potentially be done by other new struct fields independent of flags. > But that would of course require putting enough reserved fields in now and > requiring that they be zero-filled now in anticipation of such future uses, > which is not very pleasant either. > > In short, I guess I really am saying that "clone_flags_high" (or > "more_flags" or something) does seem better to me than any of the > possibilities for having more than 32 CLONE_* in the current flags word. > Overall it seems sane to: a) make it an actual 3-argument call; b) make the existing flags a u32 forever, and make it a separate argument; c) any new expansion can be via the struct, which may want to have an "c3_flags" field first in the structure. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf. _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
