On Fri, 13 Jul 2012 14:44:59 -0700 Jon Mason <[email protected]> wrote:
> A PCI-Express non-transparent bridge (NTB) is a point-to-point PCIe bus > connecting 2 systems, providing electrical isolation between the two > subsystems. > A non-transparent bridge is functionally similar to a transparent bridge > except > that both sides of the bridge have their own independent address domains. The > host on one side of the bridge will not have the visibility of the complete > memory or I/O space on the other side of the bridge. To communicate across > the > non-transparent bridge, each NTB endpoint has one (or more) apertures exposed > to > the local system. Writes to these apertures are mirrored to memory on the > remote system. Communications can also occur through the use of doorbell > registers that initiate interrupts to the alternate domain, and scratch-pad > registers accessible from both sides. > > The NTB device driver is needed to configure these memory windows, doorbell, > and > scratch-pad registers as well as use them in such a way as they can be turned > into a viable communication channel to the remote system. ntb_hw.[ch] > determines the usage model (NTB to NTB or NTB to Root Port) and abstracts away > the underlying hardware to provide access and a common interface to the > doorbell > registers, scratch pads, and memory windows. These hardware interfaces are > exported so that other, non-mainlined kernel drivers can access these. > ntb_transport.[ch] also uses the exported interfaces in ntb_hw.[ch] to setup a > communication channel(s) and provide a reliable way of transferring data from > one side to the other, which it then exports so that "client" drivers can > access > them. These client drivers are used to provide a standard kernel interface > (i.e., Ethernet device) to NTB, such that Linux can transfer data from one > system to the other in a standard way. > > Signed-off-by: Jon Mason <[email protected]> This driver does some reimplementing of standard type operations is this because you are trying to use the same code on multiple platforms? Example: + +static void ntb_list_add_head(spinlock_t *lock, struct list_head *entry, + struct list_head *list) +{ + unsigned long flags; + + spin_lock_irqsave(lock, flags); + list_add(entry, list); + spin_unlock_irqrestore(lock, flags); +} + +static void ntb_list_add_tail(spinlock_t *lock, struct list_head *entry, + struct list_head *list) +{ + unsigned long flags; + + spin_lock_irqsave(lock, flags); + list_add_tail(entry, list); + spin_unlock_irqrestore(lock, flags); +} Which are used on skb's and yet we already have sk_buff_head with locking? I know you probably are committed to this API, but is there some way to reuse existing shared memory used by virtio-net between two ports? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
