Miquel, ----- Ursprüngliche Mail ----- >> Does in-band and OOB data need to be handled together? > > Short answer: yes. > >> If so, then two requests is not a good option. > > More detailed answer: > > There is a type of MTD device (NAND devices) which are composed, for > each page, of X in-band bytes plus Y out-of-band metadata bytes. > > Accessing either the in-band data, or the out-of-band data, or both at > the same time are all valid use cases. > > * Read operation details: > From a hardware point of view, the out-of-band data is (almost) > always retrieved when the in-band data is read because it contains > meta-data used to correct eventual bitflips. In this case, if both > areas are requested, it is highly non-efficient to do two requests, > that's why the MTD core allows to do both at the same time. > * Write operation details: > Even worse, in the write case, you *must* write both at the same > time. It is physically impossible to do one after the other (still > with actual hardware, of course). > > That is why it is preferable that MUSE will be able to access both in > a single request.
By single request we meant FUSE op-codes. The NAND simulator in Userspace will see just one call. My plan is to abstract it in libfuse. Thanks, //richard
