Zynq Support

TinyThreads (since v1.5) supports ARM Cortex-A9 on Xilinx Zynq-7000 series. TinyThreads can be integrated with Xilinx SDK.

• Tested on Xilinx Vivado 2018.3

How to install

1. Confirm location of your Xilinx SDK. For example, C:\Xilinx\SDK\2018.3 on Windows.
2. Download zip or tarball from Release page and unpack on <SDK_location>/data/embeddedsw/ThirdParty/bsp/
3. If your Xilinx SDK already running, please quit and relaunch.

How to use

Applying to new projects

1. When you creates a new Application Project or Board Support Package Project, choose tinythreads from OS platform list.
2. Then, you can customize settings in tinythreads group in BSP Settings window.

Settings

Group	Name	Description
features	enable_cond	Enable condition variable APIs (pthread_cond_*)
features	enable_mutex	Enable mutex APIs (pthread_mutex_*)
features	enable_sem	Enable semaphore APIs (sem_*)
features	enable_once	Enable once control APIs (pthread_once_*)
features	enable_rwlock	Ignored. Currently reader-writer lock is not supported.
features	enable_spin	Ignored. Currently spinlock is not supported.
features	enable_sleep	Enable sleep APIs (sleep, usleep)
features	enable_profile	Enable task-switch counting (for debugging)
features	enable_name	Enable thread name APIs (pthread_{get,set}name_np) (for debugging)
others	min_stack_size	Specify default size of stacks in bytes.
others	strict_check	Enable more assertions to detect invalid state
others	thread_safe_newlib	Enable thread-safe newlib. If disabled, RAM usage will be reduced but some newlib APIs are unsafe in multi-threaded environment.
others	enable_vfp_switch	Enable VFP context switching
scheduling	preemption_enabled	Enable preemption
scheduling	preemption_interval	Specify interval of preemption in milliseconds
scheduling	priority_max	Specify maximum value of priority (means lowest priority). Valid range is 1 to 255.
scheduling	priority_min	Specify minimum value of priority (means highest priority). Valid range is 1 to 255.
scheduling	priority_default	Specify default priority. Valid range is priority_min to priority_max.
scheduling	policy_default_fifo	If enabled, FIFO will be used as the default scheduling policy. If disabled, Round-robin will be used.

Caveats

• Instruction mode
  • Only ARM mode supported. Thumb mode is not supported.
• API usage in ISR (interrupt handlers)
  • Only sem_post() can be used in ISR.
  • If other APIs are used in ISR, behavior is unpredictable.
• Interrupt usage in your application
  • TinyThreads has an instance of XScuGic internally to use tick interrupts.
  • If you want to access XScuGic, you can get a pointer to XScuGic by tth_get_xcsugic_instance() function.

    // Example
    #include "bspconfig.h"  /* For tth_get_xscugic_instance */
    #include "xscugic.h"    /* For XScuGic_xxx APIs */
    
    void setup_interrupts()
    {
        XScuGic *InstancePtr = (XScuGic *)tth_get_xscugic_instance();
        XScuGic_Connect(InstancePtr, ...); 
    }

• Newlib thread safety
  • If you disabled thread_safe_newlib, _impure_ptr in newlib will not be managed by TinyThreads. In this case, newlib functions may be unsafe when they are called from multiple threads.
• VFP usage in ISR
  • You cannot use VFP (Floating point and Advanced SIMD) in ISR. If they are used, undefined exception occurs.
• VFP usage in threads
  • If enable_vfp_switch is enabled, each thread has own VFP registers. (TinyThreads manages VFP context on demand)
    • VFP context switch needs a lot of memory copy and time, so it will be delayed until each thread accesses VFP registers.
  • If enable_vfp_switch is disabled, all threads shares VFP registers.