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Power PMAC as a Linux Computer January 2012

Power PMAC as a Linux Computer January 2012. Power PMAC Linux OS. Linux is an open-source, public-domain operating system Standard Linux has a non-preemptive multi-tasking kernel The kernel provides an execution environment for different applications

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Power PMAC as a Linux Computer January 2012

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  1. Power PMAC as a Linux ComputerJanuary 2012

  2. Power PMAC Linux OS • Linux is an open-source, public-domain operating system • Standard Linux has a non-preemptive multi-tasking kernel • The kernel provides an execution environment for different applications • The kernel implements services and interfaces for the applications • Without pre-emption, cannot do hard real-time control tasks (e.g. servos) • Power PMAC uses pre-emptive real-time kernel replacement • Xenomai open-source real-time kernel • Handles all hardware interrupts itself, blocks them from regular Linux • Runs single real-time application to handle Power PMAC “foreground” tasks (phase, servo, real-time interrupt – built-in and user-written) • Releases to regular Linux as “general-purpose OS” (GPOS) when interrupt tasks are done • Linux GPOS can run multiple applications • Dedicated Power PMAC “background tasks” • User C subroutines and application programs

  3. Basic Linux Commands • ls List directory • cd Change directory • mkdir Make directory • rmdir Remove directory • rm Delete file • mv Move or rename file • more List contents of text file • ps -e List active process • pkill Kill process • whereis Show full path to file • top –d 1 Display task manager window

  4. Power PMAC Linux File System Types • ext2 (standard Linux file system) • Write-protected with hardware jumper • Protects against flash wear, user corruption of OS files • tmpfs (temporary file system) • Used for active memory of files in RAM, lost on power cycle • vfat (Microsoft fat32 file system) • For generic USB stick access • smbfs (Samba file system) • So can access Microsoft-type network directly • nfs (Linux network file system) • So can access Linux-type network directly

  5. Key Power PMAC Linux File Folders • /opt – for Power PMAC software package, add-on packages • /var – for variable data stored by utilities and servers • /media – mount point for externally attached storage media • /media/usbdisk – mount point for USB memory stick • /media/sdcard – mount point for Secure Digital memory card • /media/shared – mount point for PC’s shared file folder • /root – administrator home folder • /bin – for essential Linux user commands • /dev – for device drivers • /lib – for essential libraries

  6. The opt/ppmac File Folder • /opt/ppmac is folder for Power PMAC software package • Power PMAC Linux applications in this folder include: • gpascii – Basic ASCII communications terminal to controller • gather_csv – Data gathering reporting program • projpp – Application and project loader program • gppmac – Background Power PMAC task execution program • stepmove, parabolicmove – Tuning-move programs • getsends – Handles sent strings from Power PMAC script programs • geterrors – Monitors for alerts of specified error conditions • Power PMAC real-time drivers also in this folder • /opt/ppmac/usrflash has saved (non-volatile) storage of user’s application – write-protected except during save operation

  7. The var/ftp/usrflash File Folder • /var/ftp/usrflash is top-level folder for active user configuration • Volatile folder in RAM (not in flash – despite folder name) • IDE loads project files into this directory on build/download • Copied from opt/ppmac/usrflash on power-on/reset • Commands in files then executed – including loading of programs into controller buffer • Copied to opt/ppmac/usrflash on save command • Sub-directory /Project contains user programs and project files • Sub-directory /PMAC Script Language contains Script motion and PLC programs • Sub-directory /C Language contains C routines and application programs • Sub-directory /Configuration contains project-management files • Sub-directory /Database contains system data for project • Note that programs can be loaded directly into controller program buffer, bypassing file system (but these cannot be saved)

  8. Files and Folders for Power PMAC Projects • Project downloading copies files from PC into /var/ftp/usrflash/ folders in RAM • Script commands are then executed from these files, loading program commands into active buffers • save command copies files into /opt/ppmac/usrflash/ folders in flash memory (previous versions retained) • Power-up/reset copies files from flash into RAM, then executes Script commands from these files • Direct loading of program commands permitted, but no save possible

  9. Power PMAC Modules gppmac C Application libplcc.so CPLC thread libppmac.so librti.so RTI thread Bkg thread High Latency User Space (100us max)‏ RTI semaphore Shared Memory pshm Low Latency Kernel Space (20us max)‏ rtpmac.ko usralgo.ko usralgo.ko libppmac.ko libppmac.ko .ko files are kernel objects (device drivers)‏ .so files are shared libraries (dll)‏

  10. Power PMAC Modules • rtpmac.ko – Interrupt handler, a few driver calls – PMAC phase, servo, RTI • libppmac.ko • Useful kernel driver function library (i.e. Custom Math Library)‏ • Functions in libppmac.ko can be called from user custom algorithms • usralgo.ko • Custom servo and phase routines written by customer in C • gppmac – executes functions in library to create PMAC background • libppmac.so • RTI thread - librti.so – custom routine created by IDE loaded by libppmac.so if UserAlgo.RtiCplc = 1 • Custom routine triggered by semaphore (special OS flag posted every RTI)‏ • Cplc thread - libplcc.so – custom routine created by IDE loaded by libppmac.so if UserAlgo.BgCplc = 1 • Custom routine triggered between each background Script PLC scan • Background Thread • Executes background Script PLC programs • Triggers CPLC thread

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