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4965ddb166
Here is the large set of USB and Thunderbolt changes for 6.12-rc1.
Nothing "major" in here, except for a new 9p network gadget that has
been worked on for a long time (all of the needed acks are here.) Other
than that, it's the usual set of:
- Thunderbolt / USB4 driver updates and additions for new hardware
- dwc3 driver updates and new features added
- xhci driver updates
- typec driver updates
- USB gadget updates and api additions to make some gadgets more
configurable by userspace
- dwc2 driver updates
- usb phy driver updates
- usbip feature additions
- other minor USB driver updates
All of these have been in linux-next for a long time with no reported
issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'usb-6.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb
Pull USB/Thunderbolt updates from Greg KH:
"Here is the large set of USB and Thunderbolt changes for 6.12-rc1.
Nothing "major" in here, except for a new 9p network gadget that has
been worked on for a long time (all of the needed acks are here)
Other than that, it's the usual set of:
- Thunderbolt / USB4 driver updates and additions for new hardware
- dwc3 driver updates and new features added
- xhci driver updates
- typec driver updates
- USB gadget updates and api additions to make some gadgets more
configurable by userspace
- dwc2 driver updates
- usb phy driver updates
- usbip feature additions
- other minor USB driver updates
All of these have been in linux-next for a long time with no reported
issues"
* tag 'usb-6.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (145 commits)
sub: cdns3: Use predefined PCI vendor ID constant
sub: cdns2: Use predefined PCI vendor ID constant
USB: misc: yurex: fix race between read and write
USB: misc: cypress_cy7c63: check for short transfer
USB: appledisplay: close race between probe and completion handler
USB: class: CDC-ACM: fix race between get_serial and set_serial
usb: r8a66597-hcd: make read-only const arrays static
usb: typec: ucsi: Fix busy loop on ASUS VivoBooks
usb: dwc3: rtk: Clean up error code in __get_dwc3_maximum_speed()
usb: storage: ene_ub6250: Fix right shift warnings
usb: roles: Improve the fix for a false positive recursive locking complaint
locking/mutex: Introduce mutex_init_with_key()
locking/mutex: Define mutex_init() once
net/9p/usbg: fix CONFIG_USB_GADGET dependency
usb: xhci: fix loss of data on Cadence xHC
usb: xHCI: add XHCI_RESET_ON_RESUME quirk for Phytium xHCI host
usb: dwc3: imx8mp: disable SS_CON and U3 wakeup for system sleep
usb: dwc3: imx8mp: add 2 software managed quirk properties for host mode
usb: host: xhci-plat: Parse xhci-missing_cas_quirk and apply quirk
usb: misc: onboard_usb_dev: add Microchip usb5744 SMBus programming support
...
278 lines
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.. SPDX-License-Identifier: GPL-2.0
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=======================================
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v9fs: Plan 9 Resource Sharing for Linux
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=======================================
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About
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=====
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v9fs is a Unix implementation of the Plan 9 9p remote filesystem protocol.
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This software was originally developed by Ron Minnich <rminnich@sandia.gov>
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and Maya Gokhale. Additional development by Greg Watson
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<gwatson@lanl.gov> and most recently Eric Van Hensbergen
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<ericvh@gmail.com>, Latchesar Ionkov <lucho@ionkov.net> and Russ Cox
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<rsc@swtch.com>.
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The best detailed explanation of the Linux implementation and applications of
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the 9p client is available in the form of a USENIX paper:
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https://www.usenix.org/events/usenix05/tech/freenix/hensbergen.html
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Other applications are described in the following papers:
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* XCPU & Clustering
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http://xcpu.org/papers/xcpu-talk.pdf
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* KVMFS: control file system for KVM
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http://xcpu.org/papers/kvmfs.pdf
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* CellFS: A New Programming Model for the Cell BE
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http://xcpu.org/papers/cellfs-talk.pdf
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* PROSE I/O: Using 9p to enable Application Partitions
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http://plan9.escet.urjc.es/iwp9/cready/PROSE_iwp9_2006.pdf
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* VirtFS: A Virtualization Aware File System pass-through
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https://kernel.org/doc/ols/2010/ols2010-pages-109-120.pdf
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Usage
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=====
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For remote file server::
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mount -t 9p 10.10.1.2 /mnt/9
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For Plan 9 From User Space applications (http://swtch.com/plan9)::
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mount -t 9p `namespace`/acme /mnt/9 -o trans=unix,uname=$USER
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For server running on QEMU host with virtio transport::
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mount -t 9p -o trans=virtio <mount_tag> /mnt/9
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where mount_tag is the tag generated by the server to each of the exported
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mount points. Each 9P export is seen by the client as a virtio device with an
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associated "mount_tag" property. Available mount tags can be
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seen by reading /sys/bus/virtio/drivers/9pnet_virtio/virtio<n>/mount_tag files.
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USBG Usage
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==========
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To mount a 9p FS on a USB Host accessible via the gadget at runtime::
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mount -t 9p -o trans=usbg,aname=/path/to/fs <device> /mnt/9
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To mount a 9p FS on a USB Host accessible via the gadget as root filesystem::
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root=<device> rootfstype=9p rootflags=trans=usbg,cache=loose,uname=root,access=0,dfltuid=0,dfltgid=0,aname=/path/to/rootfs
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where <device> is the tag associated by the usb gadget transport.
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It is defined by the configfs instance name.
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USBG Example
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============
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The USB host exports a filesystem, while the gadget on the USB device
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side makes it mountable.
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Diod (9pfs server) and the forwarder are on the development host, where
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the root filesystem is actually stored. The gadget is initialized during
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boot (or later) on the embedded board. Then the forwarder will find it
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on the USB bus and start forwarding requests.
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In this case the 9p requests come from the device and are handled by the
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host. The reason is that USB device ports are normally not available on
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PCs, so a connection in the other direction would not work.
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When using the usbg transport, for now there is no native usb host
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service capable to handle the requests from the gadget driver. For
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this we have to use the extra python tool p9_fwd.py from tools/usb.
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Just start the 9pfs capable network server like diod/nfs-ganesha e.g.::
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$ diod -f -n -d 0 -S -l 0.0.0.0:9999 -e $PWD
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Optionaly scan your bus if there are more then one usbg gadgets to find their path::
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$ python $kernel_dir/tools/usb/p9_fwd.py list
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Bus | Addr | Manufacturer | Product | ID | Path
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--- | ---- | ---------------- | ---------------- | --------- | ----
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2 | 67 | unknown | unknown | 1d6b:0109 | 2-1.1.2
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2 | 68 | unknown | unknown | 1d6b:0109 | 2-1.1.3
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Then start the python transport::
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$ python $kernel_dir/tools/usb/p9_fwd.py --path 2-1.1.2 connect -p 9999
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After that the gadget driver can be used as described above.
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One use-case is to use it as an alternative to NFS root booting during
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the development of embedded Linux devices.
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Options
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=======
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============= ===============================================================
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trans=name select an alternative transport. Valid options are
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currently:
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======== ============================================
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unix specifying a named pipe mount point
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tcp specifying a normal TCP/IP connection
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fd used passed file descriptors for connection
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(see rfdno and wfdno)
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virtio connect to the next virtio channel available
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(from QEMU with trans_virtio module)
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rdma connect to a specified RDMA channel
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usbg connect to a specified usb gadget channel
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======== ============================================
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uname=name user name to attempt mount as on the remote server. The
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server may override or ignore this value. Certain user
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names may require authentication.
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aname=name aname specifies the file tree to access when the server is
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offering several exported file systems.
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cache=mode specifies a caching policy. By default, no caches are used.
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The mode can be specified as a bitmask or by using one of the
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preexisting common 'shortcuts'.
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The bitmask is described below: (unspecified bits are reserved)
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========== ====================================================
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0b00000000 all caches disabled, mmap disabled
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0b00000001 file caches enabled
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0b00000010 meta-data caches enabled
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0b00000100 writeback behavior (as opposed to writethrough)
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0b00001000 loose caches (no explicit consistency with server)
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0b10000000 fscache enabled for persistent caching
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========== ====================================================
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The current shortcuts and their associated bitmask are:
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========= ====================================================
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none 0b00000000 (no caching)
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readahead 0b00000001 (only read-ahead file caching)
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mmap 0b00000101 (read-ahead + writeback file cache)
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loose 0b00001111 (non-coherent file and meta-data caches)
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fscache 0b10001111 (persistent loose cache)
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========= ====================================================
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NOTE: only these shortcuts are tested modes of operation at the
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moment, so using other combinations of bit-patterns is not
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known to work. Work on better cache support is in progress.
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IMPORTANT: loose caches (and by extension at the moment fscache)
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do not necessarily validate cached values on the server. In other
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words changes on the server are not guaranteed to be reflected
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on the client system. Only use this mode of operation if you
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have an exclusive mount and the server will modify the filesystem
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underneath you.
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debug=n specifies debug level. The debug level is a bitmask.
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===== ================================
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0x01 display verbose error messages
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0x02 developer debug (DEBUG_CURRENT)
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0x04 display 9p trace
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0x08 display VFS trace
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0x10 display Marshalling debug
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0x20 display RPC debug
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0x40 display transport debug
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0x80 display allocation debug
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0x100 display protocol message debug
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0x200 display Fid debug
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0x400 display packet debug
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0x800 display fscache tracing debug
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===== ================================
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rfdno=n the file descriptor for reading with trans=fd
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wfdno=n the file descriptor for writing with trans=fd
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msize=n the number of bytes to use for 9p packet payload
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port=n port to connect to on the remote server
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noextend force legacy mode (no 9p2000.u or 9p2000.L semantics)
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version=name Select 9P protocol version. Valid options are:
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======== ==============================
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9p2000 Legacy mode (same as noextend)
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9p2000.u Use 9P2000.u protocol
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9p2000.L Use 9P2000.L protocol
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======== ==============================
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dfltuid attempt to mount as a particular uid
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dfltgid attempt to mount with a particular gid
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afid security channel - used by Plan 9 authentication protocols
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nodevmap do not map special files - represent them as normal files.
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This can be used to share devices/named pipes/sockets between
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hosts. This functionality will be expanded in later versions.
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directio bypass page cache on all read/write operations
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ignoreqv ignore qid.version==0 as a marker to ignore cache
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noxattr do not offer xattr functions on this mount.
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access there are four access modes.
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user
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if a user tries to access a file on v9fs
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filesystem for the first time, v9fs sends an
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attach command (Tattach) for that user.
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This is the default mode.
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<uid>
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allows only user with uid=<uid> to access
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the files on the mounted filesystem
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any
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v9fs does single attach and performs all
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operations as one user
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clien
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ACL based access check on the 9p client
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side for access validation
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cachetag cache tag to use the specified persistent cache.
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cache tags for existing cache sessions can be listed at
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/sys/fs/9p/caches. (applies only to cache=fscache)
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============= ===============================================================
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Behavior
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========
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This section aims at describing 9p 'quirks' that can be different
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from a local filesystem behaviors.
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- Setting O_NONBLOCK on a file will make client reads return as early
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as the server returns some data instead of trying to fill the read
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buffer with the requested amount of bytes or end of file is reached.
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Resources
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=========
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Protocol specifications are maintained on github:
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http://ericvh.github.com/9p-rfc/
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9p client and server implementations are listed on
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http://9p.cat-v.org/implementations
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A 9p2000.L server is being developed by LLNL and can be found
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at http://code.google.com/p/diod/
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There are user and developer mailing lists available through the v9fs project
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on sourceforge (http://sourceforge.net/projects/v9fs).
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News and other information is maintained on a Wiki.
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(http://sf.net/apps/mediawiki/v9fs/index.php).
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Bug reports are best issued via the mailing list.
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For more information on the Plan 9 Operating System check out
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http://plan9.bell-labs.com/plan9
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For information on Plan 9 from User Space (Plan 9 applications and libraries
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ported to Linux/BSD/OSX/etc) check out https://9fans.github.io/plan9port/
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