a9e88a0a49
If the networking stack fails to provide a transmit time stamp, then we might feed uninitialized stack data to the CMSG(3) macros. This can result in a segfault or other badness. The fix is to simply clear the control buffer in advance. Signed-off-by: Richard Cochran <richardcochran@gmail.com> |
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|---|---|---|
| COPYING | ||
| README.org | ||
| bmc.c | ||
| bmc.h | ||
| clock.c | ||
| clock.h | ||
| config.c | ||
| config.h | ||
| contain.h | ||
| ddt.h | ||
| default.cfg | ||
| ds.h | ||
| fd.h | ||
| foreign.h | ||
| fsm.c | ||
| fsm.h | ||
| hwstamp_ctl.c | ||
| makefile | ||
| mave.c | ||
| mave.h | ||
| missing.h | ||
| msg.c | ||
| msg.h | ||
| pdt.h | ||
| phc.c | ||
| phc.h | ||
| phc2sys.c | ||
| pi.c | ||
| pi.h | ||
| port.c | ||
| port.h | ||
| print.c | ||
| print.h | ||
| ptp4l.c | ||
| servo.c | ||
| servo.h | ||
| servo_private.h | ||
| tmtab.c | ||
| tmtab.h | ||
| tmv.h | ||
| transport.c | ||
| transport.h | ||
| udp.c | ||
| udp.h | ||
| util.c | ||
| util.h | ||
README.org
- Introduction
- License
- Goals and Features
- System Requirements
- Installation
- Getting Involved
- Other PTP Applications
Introduction
This software is an implementation of the Precision Time Protocol (PTP) according to IEEE standard 1588 for Linux. The dual design goals are to provide a robust implementation of the standard and to use the most relevant and modern Application Programming Interfaces (API) offered by the Linux kernel. Supporting legacy APIs and other platforms is not a goal.
License
The software is copyrighted by the authors and is licensed under the GNU General Public License. See the file, COPYING, for details of the license terms.
Goals and Features
- Supports hardware and software time stamping via the Linux SO_TIMESTAMPING socket option.
- Supports the Linux PTP Hardware Clock (PHC) subsystem by using the clock_gettime family of calls, including the new clock_adjtimex system call.
- Implements Boundary Clock (BC) and Ordinary Clock (OC).
- Transport over UDP/IPv4, UDP/IPv6, and raw Ethernet (Layer 2).
- Modular design allowing painless addition of new transports and clock servos.
System Requirements
In order to run this software, you need to run a recent Linux kernel version 3.0 or newer, and the kernel header files must available at compile time.
In addition, you will also need to have either:
- A supported Ethernet MAC device.
- A supported PHY device paired with a MAC that allows time stamping in the PHY (indicated by PHY=Y in the table below).
Linux Kernel Support
In order to support PTP, the operating system needs to provide two services: network packet time stamping and clock control. In 2009, Patrick Ohly added a new socket option called SO_TIMESTAMPING for packet time stamping, especially for PTP. This work appeared in Linux version 2.6.30.
In July of 2011, the PTP Hardware Clock (PHC) subsystem was merged into Linux version 3.0. The PHC code provides a driver framework and the user space API for clock control.
Driver Support Matrix
The table below shows the Linux drivers that support the new API. The meaning of the column abbreviations is as follows.
-
SOTS: SO_TIMESTAMPING support. This comes in three flavors.
- RAW: Supports time stamping using the PHC time values.
- SW: Supports software time stamping using the system time.
- SYS: Supports time stamping using PHC time values scaled to the system time. This is a legacy mode and its use in new drivers is discouraged.
- PHC: PTP Hardware Clock support. These drivers will offer a character device that allows direct control of the hardware clock.
- PHY: Supports time stamping in the PHY. This indicates an Ethernet MAC driver supporting SO_TIMESTAMPING and PHC in the PHY. If you have or build a computer that combines this MAC with a PTP capable PHY, then it will work with the Linux PHC subsystem.
- VER: Linux kernel version when the PTP API support was added.
Hardware Timestamping
| Driver | Hardware | SOTS | PHC | PHY | VER |
| bfin_mac | Analog Blackfin | SYS | N | NA | pre 3.0 |
| igb | Intel 82576, 82580 | SYS | N | NA | pre 3.0 |
| dp83640 | Nat Semi PHYTER | RAW | Y | NA | 3.0 |
| gianfar | Freescale eTSEC PowerPC | RAW | Y | NA | 3.0 |
| ptp_ixp46x | Intel IXP465 | RAW | Y | NA | 3.0 |
Software Timestamping
| Driver | Hardware | SOTS | PHC | PHY | VER |
| davinci_emac | TI DaVinci, Sitara | SW | N | Y | 3.1 |
| dnet | Dave Ethernet MAC | SW | N | Y | 3.1 |
| emaclite | Xilinx Ethernet Lite | SW | N | Y | 3.1 |
| ethoc | OpenCores 10/100 MAC | SW | N | Y | 3.1 |
| fec | Freescale Coldfire | SW | N | Y | 3.1 |
| fec_mpc52xx | Freescale MPC5200 | SW | N | Y | 3.1 |
| fs_enet | Freescale MPC512x | SW | N | Y | 3.1 |
| ixp4xx_eth | Intel IXP4xx | SW | N | Y | 3.0 |
| lib8390 | Asix AX88796 | SW | N | Y | 3.1 |
| lib8390 | Various 8390 based HW | SW | N | N | 3.1 |
| ll_temac | Xilinx LL TEMAC | SW | N | Y | 3.1 |
| macb | Atmel AT32, AT91 | SW | N | Y | 3.1 |
| mv643xx_eth | Marvell Discovery, Orion | SW | N | Y | 3.1 |
| pxa168_eth | Marvell pxa168 | SW | N | Y | 3.1 |
| r6040 | RDC Ethernet MAC | SW | N | Y | 3.1 |
| smsc911x | SMSC LAN911x, LAN921x | SW | N | Y | 3.1 |
| smsc9420 | SMSC LAN9420 PCI | SW | N | Y | 3.1 |
| stmmac | STM Synopsys IP Core | SW | N | Y | 3.1 |
| tg3 | Broadcom Tigon3 PCI | SW | N | Y | 3.1 |
| ucc_geth | Freescale QE Gigabit | SW | N | Y | 3.1 |
Installation
Linux kernel
There are many ways of getting a precompiled Linux kernel or compiling your own, so this section is only meant as an example. It is important to have the kernel headers available when compiling the Linux PTP stack.
export ARCH=x86 export CROSS_COMPILE= export KBUILD_OUTPUT=/home/richard/kernel/ptp_debian mkdir -p $KBUILD_OUTPUT cp /boot/config-2.6.38-bpo.2-686 $KBUILD_OUTPUT/.config make oldnoconfig make menuconfig time make -j4 make headers_install
Here is a table of kernel configuration options needed for PTP support. In addtion to these, you should enable the specific Ethernet MAC and PHY drivers for your hardware.
| Option | Description |
| CONFIG_EXPERIMENTAL | Required |
| CONFIG_PPS | Required |
| CONFIG_NETWORK_PHY_TIMESTAMPING | Timestamping in PHY devices |
| PTP_1588_CLOCK | PTP clock support |
PTP stack
- Just type 'make'
- If you compiled your own kernel (and the headers are not installed into the system path), then you should set the KBUILD_OUTPUT environment variable as in the example, above.
- There is no install target. You can run the program in place or copy it into the system path, like /usr/local/bin.
Getting Involved
The software development is hosted at Source Forge.
https://sourceforge.net/projects/linuxptp/
Reporting Bugs
Please report any bugs or other issues with the software to the linuxptp-users mailing list.
Development
If you would like to get involved in improving the software, please join the linuxptp-devel mailing list.
Other PTP Applications
As of yet there are no other open source applications making use of the new Linux APIs for PTP. However, patches are available for the ptpd program adapting it to the new calls. These patches do not really turn the ptpd into a perfect solution for hardware time stamping under Linux. Instead, they merely illustrate how the newer APIs work.
You can get the patches over at github. There are two branches, phc1 and phc2, for PTP versions 1 and 2, respectively.
- git://github.com/richardcochran/ptpd-phc.git
- https://github.com/richardcochran/ptpd-phc