Messages in this thread |  | | | Date | Wed, 18 Jan 2006 18:57:41 -0800 | | From | Greg KH <> | | Subject | Re: RFC: ipath ioctls and their replacements |
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On Wed, Jan 18, 2006 at 04:43:31PM -0800, Bryan O'Sullivan wrote: > Opening the /dev/ipath special file assigns an appropriate free > unit (chip) and port (context on a chip) to a user process.
Shouldn't you just open the proper chip device and port device itself? That drops one ioctl.
> Think of it as similar to /dev/ptmx for ttys, except there isn't > a devpts-like filesystem behind it. Once a process has > opened /dev/ipath, it needs to find out which unit and port it > has opened, so that it can access other attributes in /sys. To > do this, we provide a GETPORT ioctl.
> USERINIT and BASEINFO work with mmap to set up direct access to > the hardware for user processes. We intend to turn these into a > single ioctl, USERINIT. This copies a substantial amount of > information to and from userspace.
Why not just use mmap? What's the special needs?
> RCVCTRL enables/disables receipt of packets.
sysfs file.
> SET_PKEY sets a partition key, essentially telling hardware > which packets are interesting to userspace.
sysfs file.
> UPDM_TID and FREE_TID are used for RDMA context management.
sysfs files.
> WAIT waits for incoming packets, and can clearly be replaced by > file_ops->poll.
Use poll.
> GETCOUNTERS, GETUNITCOUNTERS and GETSTATS can all be replaced by > files in sysfs.
good.
> For subnet management: > > GETLID, SET_LID, SET_MTU, SET_GUID, SET_MLID, GET_MLID, > GET_DEVSTATUS, GET_PORTINFO and GET_NODEINFO can all be replaced > by files in sysfs. > > SET_LINKSTATE changes the link state. > > SEND_SMA_PKT and RCV_SMA_PKT send and receive subnet management > packets. I *think* they could be replaced by read and write > methods on a new special file, although the semantics aren't a > super-clean match.
Use netlink for subnet stuff.
> For diagnostics: > > DIAGENTER and DIAGLEAVE put the driver into and out of diag > mode. These could be replaced by open/close of a special file.
Use debugfs.
> DIAGREAD and DIAGWRITE perform direct accesses to the device's > PCI memory space. I think these could be replaced by read and > write, but they are again subject to the make-coworker-barf > problem.
Use debugfs.
> HTREAD and HTREAD perform direct accesses to the device's PCI > config space. Same disagreement problem as DIAGREAD and > DIAGWRITE.
Use the pci sysfs config files, don't duplicate existing functionality.
> SEND_DIAG_PKT can be replaced with whatever sends and receives > subnet management packets, as above.
netlink or debugfs.
Hope this helps,
greg k-h - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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