Messages in this thread | | | Date | Thu, 30 Mar 2006 09:33:42 +0200 | From | Jens Axboe <> | Subject | Re: [PATCH][RFC] splice support |
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On Wed, Mar 29 2006, Andrew Morton wrote: > Jens Axboe <axboe@suse.de> wrote: > > > > > > Right now "flags" doesn't do anything at all, and you should just pass in > > > > zero. > > > > > > In that case perhaps we should be enforcing flags==0 so that future > > > flags-using applications will reliably fail on old flags-not-understanding > > > kernels. > > > > > > But that won't work if we later define a bit in flags to mean "behave like > > > old kernels used to". So perhaps we should require that bits 0-15 of > > > `flags' be zero and not care about bits 16-31. > > > > > > IOW: it might be best to make `flags' just go away, and add new syscalls in > > > the future as appropriate. > > > > Not if flags == 0 maintains the same behaviour. The only flag I can > > think of right now is the 'move' or 'gift' flag, meaning that the caller > > wants to migrate pages from the pipe instead of copying them. I'd > > imagine we'd get that in way before 2.6.17 anyways, so I think we're > > fine. > > OK.. Do you plan to make it reject unrecognised flags?
Depends, not sure if eg a 'move' flag should be a hard or soft indication. Say we can't move a page and the caller asked us to migrate, we'd probably just do the sane thing and copy that one page. It would be silly to fail that request entirely.
-- Jens Axboe
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