ARM Linux & GNU. Philippe Robin. Beijing June 2004

Transcription

1 ARM Linux & GNU Philippe Robin Beijing June

2 Outline ARM Embedded Linux ARM & Open Source Model Architecture and Platforms Support Linux 2.4 kernel Linux 2.6 kernel GNU GCC tool chain Debugging Linux resources Cooperation 2

3 Linux Progress in Embedded Space Linux making inroads in embedded space PDAs Mobile phones Netwoking STB Increased kernel functionality Real-time Networking Power management Security Large developer community Newsgroups Communities: ipaq, Zaurus CELF Journals Etc. 3

4 ARM Prime Position in Embedded Embedded Linux developers will base more projects on ARM than x86 processors in future projects Embedded Linux Market Survey Linux Devices 4

5 ARM Architecture Evolution ARMv ARMv6Z TrustZone, IEM* ARMv6T2 Thumb-2 ISA 2000 ARMv6 SIMD Media ISA 1998 ARMv5TEJ Jazelle Java Acceleration 1995 ARMv5TE DSP Instructions ARMv4T Thumb ISA ISA 5

6 ARM Architecture Roadmap Long-term roadmap to address high and low end Superscalar for high-end platforms Low-end cores for microcontrollers and WLAN New technology to address real design challenges Thumb-2 for code density, power and performance TrustZone for design of secure systems Extensions for multimedia New system level technology for performance and power Symmetric Multiprocessor for next generation systems AMBA AXI interconnect for high bandwidth utilisation Intelligent Energy Management for low-power 6

7 Linux and Architecture Support ARM ARCHITECTURES V4 V5TE Jazelle (option) V5TEJ TrustZone V6 Intelligent Energy Controller (IEC) V7 Linux 2.4 kernel Linux Kernel Linux 2.6 kernel Linux 2.7 kernel Preemtion, 0(1) scheduler, New Posix Thread Library (NPTL), Power Management etc 7

8 Open Source Model Commercial Linux Providers Gatekeepers Other organisations -Embedded Linux Consortium -Embedix -CELF Open Source Repository ARM Source Tree Architecture & Platform Support ARM Linux Open Source Tree Other Contributors: -Platforms (Zaurus, ipaq ) -Debian -Etc 8

9 ARM Contributions to Open Source ARM Contribute Architectural support to Linux kernel and associated GNU projects New architectures and ARM cores ARMv6 (ARM1136, ARM1176), ARMv7... New technology Power Management (IEM), SMP, TrustZone Promote standardization initiatives New ARM ABI Promote interoperability and choice Early contribution to promote adoption from the community Cooperation with partners and gatekeepers Promote active participation and contributions to the open source 9

10 Early Architectural Support Linux is used internally at ARM to Validate new ARM cores and technology With simulation models, FPGA and Silicon Contribute architectural support to GCC GCC is currently the main compiler used to build Linux kernel and applications Promote new ARM ABI to allow more choices and inter-operability between tool chains 10

11 ARM Development Platforms Integrator Family Versatile Family Compact Platform Versatile Platform Baseboard Logic Modules Core Modules Interface Modules Logic Tile Analyzer Tile 11

12 ARM Cores and Platform Support Currently main Linux kernel has support for: ARM720T, ARM92x, ARM102x and ARM11 based cores ARM development platforms ARM Integrator family Versatile board BSP availability ARM (early access) Open source ( availability usually coincide with hardware availability 12

13 Linux 2.4 kernel Stable version Feature freeze Only bug fixes are now being integrated Current includes support for: ARM cores up to ARMv6 Legacy mode, not optimised Integrator AP and CP Versatile PB Patch available from ARM 13

14 Linux 2.6 kernel is the current development version Version includes support for: ARM cores up to architecture v6 including: ASIDS, Atomic instructions, physically tagged cache, CPS instructions Integrator AP, CP and Versatile Platforms Including the following Primecell peripherals: Serial, Timers, Interrupt controller, KMI, Ethernet, VGA/LCD Peripherals being added in 04Q2 AACI, VIC, VFP9 MMC, RTC, I2C USB (Transdimension), DoC (M-Systems) 14

15 Hardware Floating Point Need associated compiler support Now available in GCC 3.4 Linux kernel support now added to 2.6 kernel Validated on ARM Versatile platform using VFP9 Availability 2004Q2 (aim for Linux kernel) 15

16 Increased Performance & Low Power More bits to more places Signal processing instructions SIMD, MOVE media instructions Multi-layer bus architectures More instructions per cycle Deeper pipelines Superscalar, VLIW More algorithms at once Coprocessors, accelerators More applications Multiple processors MPEG video encode Animations & virus checking Intelligent Energy Management Image Processing Picture / Camera Processing MP3 Music Image Scrolling Processing keyboard input 16

17 ARM MPCore Platform Configurable ARMv6 architectural core Implement between 1 and 4 processors Provides up to 2600 DMIPS performance Integral interrupt distribution and control unit Flexible software support Symmetric multiprocessing (SMP) OS dynamically shares task across multiple CPU Coherent and consistent view of memory Asymmetric multiprocessing (AMP) Programmer statically assigns tasks to CPU Isolate tasks from each other SoC system compatibility AMBA AXI bus inter-connect RealView development tools PrimeCell L220 L2 cache controller 17

18 ARM Linux SMP Support Linux kernel already has SMP support for multiple architectures Implications on development tool chain Multi-threading (TLS) Debugging tools ARMv6 architecture + extensions Physically indexed, physically tagged coherent data cache Write allocation in Write-Back regions 64-bit non-bus locking LDRDEX/STRDEX Thread context registers Weakly ordered memory model, with memory barriers and sequential consistency for certain memory regions Initial validation on modified ARM926EJ-S cores running Linux on ARM Integrator/CP Need hardware support for cache coherency, synchronization 18

19 ARM Intelligent Energy Management (IEM) Controlling run-time voltage reduces energy consumed from battery when maximum performance is not required. Reducing energy consumed, Extends battery life or Enables additional functionality for same battery Reduces battery size for same functionality Greater user benefits and/or lower mfg. cost Reducing frequency reduces average power consumption and associated heating Can also help to reduce packaging costs 19

20 ARM Linux - IEM Current prototype developed on Linux kernel Used as technology demonstrator Complementary to other existing technologies such as Montavista Dynamic Power Management (DPM) Works along hardware components (IEC) Participate to CELF Power Management Group Define common kernel interface to power management IEM documentation 20

21 Future Architectural Support ARM1176JZ-S support Thumb2 support ARMv7 (Tiger) 21

22 ARM GNU Tools GCC currently is the main compiler used to build Linux kernels and applications Open source Extensive ARM core support Cross-compiler used to generate for ARM Host / Target development model Built with associated libraries (Glibc, pthread ) Delicate to build stable versions 22

23 ARM Contribution to GNU Tools Follow evolution of the ARM Architecture Recently added ARMv6 support Adoption of the new ARM ABI Initial ARM ABI support for GCC end 2004 Inter-operability between tool chains Publicly available Bi-annual source and binary releases Snapshots and binary packages Open source mailing lists Cooperation with CodeSourcery is one of GCC main gatekeepers 23

24 ARM GCC Processor Support Currently support up to ARMv6 Architecture ARMv6 instructions (supported by compiler) Hardware VFP BE8 (new ARM ABI) ARM1176JZ-S CPU support ARMv6 interrupt instructions 24

25 ARM GNU Tools Planned Work Next release planned for 2004Q4 New ARM ABI support Enables interlink with ARM Compiler 2005 Q4 Thumb2 support CPU support for ARM1156T2(F)-S 2006 Q2 Tiger CPU support 25

26 ARM GCC ABI and Accessibility Adoption of the new ABI for the ARM Architecture Better portability of binary code Allows greater interoperability between proprietary tool chains (RVCT, etc.) Open access of pre-built GNU binaries Facilitate access to ARM development environment Enable early adoption of new architectural features 26

27 ARM Linux - Debug GDB has architectural support added for new cores Currently ARMv6 support GDB Multi-thread debug Ensure working debug functionality in GDB for multithreaded applications ARM RealView debugger targeting Linux Debug Linux kernels using ARM RealView Debugger Halted System Debug for kernel and loadable modules Provide visibility of Linux resources (processes, threads, semaphores ) Plan for Running System Debug Debugging of threads without stopping the whole system 27

28 ARM Linux Building Blocks Compilation tool chain Boot Loader Kernel distribution and patches Filesystem and applications Debug and Validation tools Additional links 28

29 ARM Linux Tool Chain Need arm-linux build of the GNU compiler Cross-compilation from Unix (Linux or Solaris) or Windows host Snapshots available at Choice of C library Glibc standard GNU C library uclibc Newlib smaller library Decide on which library to use when building the cross compilation tool chain 29

30 Linux - Boot Loader Boot Loader is used to Initialise platform, Load and run Linux kernels Can download kernel using tftp/bootp Access from flash if kernel resides in Flash Setup various initialisation parameters: command line: root=/dev/nfs. Platform ID (stored in r1) Some boot loaders used for ARM platforms: U-Boot ( RedBoot ( 30

31 Building Linux Kernels Download reference kernel Download and apply associated ARM patch This is applied on unpacked base kernel Add additional patches as appropriate Configure the kernel (i.e. make xconfig ) Choose architecture, development platform, devices and functionality needed Build the kernel Ensure the right link is set in main Makefile to point at the cross compiler location 31

32 Running Linux kernels Built image is in arch/arm/boot directory Loading and running the image on the target: Use BootLoader Either via network (tftp/bootp) or from flash Use Debugger Load image as raw binary for uncompressed Image) Set platform ID in r1 and initialise r0, r2 Disable semihosting and vector catch Set pc=0x8000 and run the kernel 32

33 Linux Filesystem Contains system utilities and applications Busybox for base utilities ( Need C library either Glibc or Newlib Additional utilities such as: Sysvinit, shells, ftpd, telnet Graphical windowing system and applications: X11 environment: Microwindows: Qt/Qtopia: Access from Flash or via NFS From Flash can use cramfs, romfs 33

34 Linux Debugging Kernel debug With JTAG connection use commercial debugger for early kernel bring up Use Kgdb to debug kernel Commercial debuggers offer additional features to debug and profile the Linux kernel: Choice of halted/running system debug Profiling Application debug Use GDB over serial or networking link Either natively or in cross-debug environment Choice over graphical front-end used Use commercial debuggers for debugging over JTAG 34

35 Additional open source links Gnu Debugger - Linux Test Project - Test coverage of the kernel Linux Trace Toolkit - Acquire and display kernel trace information Guide to porting Linux on new ARM hardware Guide to building Linux system from scratch Other useful resources

36 Cooperation Commercial Linux distributions Montavista ( Metrowerks ( LynuxWorks ( Lineo ( Consumer Electronic Linux Forum (CELF) ARM is Associate Member Participate to Working Groups to improve ARM/Linux support for Embedded platforms Developer forums and communities 36