> > > Agreed. But we can ask the HCD how much to reserve allocating the urb. > > > > And that would work ... how? Remember it's a multi-dimensional problem. > > .... > > That essential information is unavailable when the URB is allocated. > > It's known for the first time when the URB is submitted. > > Could we add a pointer to a reserve page to the urb structure ? > Can you give an upper bound on the amount of memory needed ?
That's all a function of the URB that's submitted ... including all the factors I mentioned, and a few more. A given URB clearly needs a certain number of TDs; a different URB can need more (or less) even if it's the same size (and type) transfer. > Unfortunately, to be safe in the writeout path, no memory at all must be allocated That sounds like the problem is rather overconstrained. Surely there's a more reasonable characterization of the issue than that ... And page writes to remote disks (NFS etc) surely ought to work too, such as for mmapped application data (or even swapfiles). Network I/O tends to allocate memory, yes? Paging over NFS worked since NFS first existed. - Dave _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
