On Mon, 24 Jun 2019, Suwan Kim wrote: > > > + hcd->self.sg_tablesize = ~0; > > > + hcd->self.no_sg_constraint = 1; > > > > You probably shouldn't do this, for two reasons. First, sg_tablesize > > of the server's HCD may be smaller than ~0. If the client's value is > > larger than the server's, a transfer could be accepted on the client > > but then fail on the server because the SG list was too big. On the other hand, I don't know of any examples where an HCD has sg_tablesize set to anything other than 0 or ~0. vhci-hcd might end up being the only one. > > Also, you may want to restrict the size of SG transfers even further, > > so that you don't have to allocate a tremendous amount of memory all at > > once on the server. An SG transfer can be quite large. I don't know > > what a reasonable limit would be -- 16 perhaps? > > Is there any reason why you think that 16 is ok? Or Can I set this > value as the smallest value of all HC? I think that sg_tablesize > cannot be a variable value because vhci interacts with different > machines and all machines has different sg_tablesize value. I didn't have any good reason for picking 16. Using the smallest value of all the HCDs seems like a good idea. Alan Stern
