On Thursday 08 November 2007 13:41:16 Anthony Liguori wrote: > Rusty Russell wrote: > > On Thursday 08 November 2007 04:30:50 Anthony Liguori wrote: > >> I would prefer that the virtio API not expose a little endian standard. > >> I'm currently converting config->get() ops to ioreadXX depending on the > >> size which already does the endianness conversion for me so this just > >> messes things up. I think it's better to let the backend deal with > >> endianness since it's trivial to handle for both the PCI backend and the > >> lguest backend (lguest doesn't need to do any endianness conversion). > > > > -ETOOMUCHMAGIC. We should either expose all the XX interfaces (but this > > isn't a high-speed interface, so let's not) or not "sometimes" convert > > endianness. Getting surprises because a field happens to be packed into 4 > > bytes is counter-intuitive. > > Then I think it's necessary to expose the XX interfaces. Otherwise, the > backend has to deal with doing all register operations at a per-byte > granularity which adds a whole lot of complexity on a per-device basis > (as opposed to a little complexity once in the transport layer). Huh? Take a look at the drivers, this simply isn't true. Do you have evidence that it will be true later? Plus your code will be smaller doing a single writeb/readb loop than trying to do a switch statement. > You really want to be able to rely on multi-byte atomic operations too > when setting values. Otherwise, you need another register to just to > signal when it's okay for the device to examine any given register. You already do; the status register fills this role. For example, you can't tell what features a guest understands until it updates the status register. Hope that clarifies, Rusty. _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/virtualization
