= GIET_VM / User-Level System Calls = The [source:soft/giet_vm/giet_libs/stdio.c stdio.c] and [source:soft/giet_vm/giet_libs/stdio.h stdio.h] files define all system calls provided to user applications by the GIET-VM. System calls are prefixed by ''giet_''. [[PageOutline]] All these functions use a ''syscall'' instruction to enter the system. For most system calls, in case of failure (illegal arguments), the calling thread is killed with a ''giet_pthread_exit()''. == __Processor related system calls__ == These system calls access the MIPS32 protected registers CP0_PROCID and CP0_TIME. === 1) void '''giet_proc_xyp'''( unsigned int* cluster_x, unsigned int* cluster_y unsigned int* p )=== Each thread is statically allocated to one processor P[x,y,p] in the boot phase, and there is no thread migration. This function returns the processor identifiers (x,y,p) for the processor running the calling thread. It access the wired global processor index stored in the CP0_PROCID register. The and arguments are the the cluster coordinates. The

argument is the processor local index. The format is CP0_PROCID = ( ( cluster_x << Y_WIDTH + cluster_y ) << P_WIDTH ) + lpid === 2) unsigned int '''giet_proctime'''() === This function returns the local processor time from the CP0_TIME register (number of cycles from reset), This register is a 32 bits wrapping register === 3) unsigned int '''giet_rand'''() === This function returns a pseudo-random value derived from both the CP0_PROCID and CP0_TIME registers. The value is always between 0 & 65535. == __Thread related system calls__ == The GIET-VM support a subset of the POSIX Threads API, defined below. . The ''pthread_t'' and ''pthread_attr_t'' types are defined in the [source:soft/giet_vm/giet_libs/stdio.h stdio.h] file. === 1) int '''giet_pthread_create'''( pthread_t* trdid , pthread_attr_t* attr , void* function , void* arg ) === This functions activates one thread that will execute the C function defined by the argument. All thread activated by this system call must have been defined in the application mapping. The argument (pthread attributes) is not supported, and should be set to NULL : The stack size must be defined in the mapping, and the pthread is activated in ''attached'' mode. The argument is a pointer on an user-defined structure containing the arguments to be passed to the called function. It can be set to NULL if the function has no arguments. The thread identifier stored in the argument by the kernel is unique in a given vspace: It is actually build from the 4 following informations : [x,y,p,ltid] where x,y,p are the processor coordinates, and ltid is the thread index in the scheduler. Return 0 if success. Return -1 if no matching thread. Return -2 if attr not NULL. === 2) void '''giet_pthread_exit'''( void* string ) === This function send a KILL signal to the calling thread, that is immediately desactivated, and goes to the ''blocked'' state. All resources dynamically allocated to the thread, such as private peripheral channels are released. The user defined message is displayed on the kernel terminal TTY0. === 3) int '''giet_pthread_join'''( pthread_t trdid , void* ptr ) === This blocking function can be used to detect completion of a thread previously activated by a giet_pthread_create(). It returns only when the thread identified by the argument is desactivated. The argument is not supported, and should be set to NULL. Return 0 if success. Return -1 if no matching thread. Return -2 if ptr not NULL === 4) int '''giet_pthread_kill'''( pthread_t trdid , int signal ) === This function send a KILL signal to the thread identified by the argument, in the same space as the calling thread. If the argument has a non zero value, the target thread will be deactivated at the next context switch. If the argument is zero, the thread existence is checked, but the KILL signal it is not sent. Return 0 if success. Return -1 if no matching thread. === 5) void '''giet_pthread_yield'''() === The thread calling this function is descheduled and the processor is allocated to another thread. The calling thread is not deactivated and stay in the ''runable'' state. The following functions define various GIET_VM specific extensions to the POSIX threads API. === 6) void '''giet_pthread_assert'''( unsigned int condition, char* string ) === This function is an extension to the POSIX standard. It send a KILL signal and deactivates immediately the calling thread (as does the giet_pthread_exit() function), with a message on the kernel TTY0, if the argument has a zero value. The message is defined by the argument. === 7) void '''giet_pthread_control'''( unsigned int command , char* vspace , char* thread ) === This function is an extension to the POSIX standard. It execute the command defined by the argument for the thread identified by the and arguments. The supported command types are: * '''THREAD_CMD_PAUSE''' : The target thread is deactivated. It goes immediately to the ''blocked'' state, and will not be scheduled until the thread is reactivated. The thread context (including the resources dynamically allocated to the thread) is not modified. * '''THREAD_CMD_RESUME''' : The target thread is reactivated. It goes immediately to the ''runable'' state, and can be rescheduled at the next context switch to resume execution. * '''THREAD_CMD_CONTEXT''' : Display the context of the target thread on the TTY allocated to the calling thread. == __Application related system calls__ == === 1) void '''giet_exec_application'''( char* vspace_name ) === This function starts execution for the the application identified by the argument. The application data segments are (re)loaded into memory from the .elf file. Only thread that has the ''is_main'' flag set in the mapping is activated. === 2) void '''giet_kill_application'''( char* vspace_name ) === This function kill the application identified by the argument: All application threads defined in the mapping receive a KILL signal and will be deactivated at the next context switch. The private peripherals or coprocessors are released. The physical memory allocated to the killed application segments is not released. === 3) void '''get_applications_status'''( char* vspace_name ) === This function displays, for application identified by the argument, the status of each thread defined in the vspace. If the argument is NULL, it displays the status of all mapped applications. == __Coprocessors related system calls__ == The GIET_VM allows an user applications to use hardware accelerators (called coprocessors). These coprocessors can be distributed in the architecture, but there is at most one coprocessor per cluster. To be supported by the GIET_VM, a coprocessor must use the '''vci_mwmr_dma''' component, that is a generic multi-channels DMA controller. The '''vci_mwmr_dma''' component provides to a coprocessor a variable number of TO_COPROC or FROM_COPROC ports, that implement FIFO interfaces. Coprocessor can request to transfer one or several bursts of 32 bits words, without address. The burst size (generally a cache line), the number of TO_COPROC and FROM_COPROC ports, and the number of bursts for a given port are hardware parameters, depending on the coprocessor type. Each port define a private communication channel between the coprocessor and a user memory buffer. The total number of channels cannot be larger than 16. A channel is identified by an index, and the TO_COPROC channels have the smallest indexes. The user application must use the ''giet_coproc_alloc()'' system call to get a private hardware coprocessor. Then it must use the ''giet_coproc_channel_init()'' system call to configure the TO_COPROC/FROM_COPROC channels. Finally, the coprocessor and the communication channels are activated by the ''giet_coproc_run()'' system call. The '''vci_mwmr_dma''' component implements two transfer modes: * In '''MODE_MWMR''', each channel FSM implements the 7 steps MWMR protocol, and transfer an "infinite" data stream, between one coprocessor port and a MWMR software FIFO in memory. The ''giet_coproc_run()'' system call is non blocking, as the synchronisation is done through the MWMR FIFOs (no transfer completion event). The MWR IRQ is only asserted if a VCI error is reported in a memory access. * In '''MODE_DMA_IRQ''' or '''MODE_DMA_NO_IRQ''', each channel FSM transfers a single buffer between one coprocessor port and the memory, and keep blocked when the transfer is completed. - In '''MODE_DMA_IRQ''', the calling thread is descheduled, after coprocessor activation, in the ''giet_coproc_run()'' system call. It is rescheduled by the MWR IRQ signaling the global completion. The _mwr_isr() scan all channels status registers to report possible addressing errors, and reset the communication channels. - In '''MODE_DMA_NO_IRQ''', the ''giet_coproc_run()'' system call returns after coprocessor activation, and the user application must use the blocking ''giet_coproc_completed()'' system call that directly scan the channels registers to detect completion, report errors, and reset the channels. The VCI transactions corresponding to different TO_COPROC / FROM_COPROC channels are interleaved and parallelized on the VCI network. Besides the TO_COPROC/FROM_COPROC communication channels, the '''vci_mwmr_dma''' component support up to 16 coprocessor-specific '''configuration''' or '''status''' registers. * The '''configuration''' registers are Read and Write. * The '''status''' registers are Read only. '''WARNING''': The GIET-VM supports at most one hardware coprocessor per cluster. '''WARNING''': For a given coprocessor, all channels must be running in the same mode. '''WARNING''' : For all channels, the memory buffer base address and size must be multiple of the hardware burst size. '''WARNING''': All coprocessors must have at least one '''configuration''' register : writing a non zero value in register[0] activates the coprocessor; writing a zero value deactivates the coprocessor. The list of currently supported coprocessors and their characteristics are defined below : || coproc_ type || Function || nb_status || nb_config || nb_from_coproc || nb_to_coproc || || MWR_SUBTYPE_GCD || Greater Common Divider || 0 || 1 || 1 || 2 || || MWR_SUBTYPE_DCT || Discrete Cosinus Transform || 0 || 1 || 1 || 1 || || MWMR_SUTYPE_CPY || Memory Copy || 0 || 1 || 1 || 1 || === 1) void '''giet_coproc_alloc'''( unsigned int cluster_xy , unsigned int coproc_type , unsigned int* return_info ) === This function allocates a private coprocessor of type , located in cluster identified by the arguments. It takes the lock granting exclusive ownership to the calling application. In the current implementation, the calling thread exit if there is no coprocessor of requested type in cluster[x,y]. The supported values for the argument are specified above (and actually defined in the mapping_info.h file). In case of success, it returns the coprocessor characteristics in the variable. The is structured in 4 fields : nb_to_coprocs = info[7:0] / nb_from_coproc = info[15:8] / nb_config = info[23:16] / nb_status = info[31:24] === 2) void '''giet_coproc_release'''( unsigned int cluster_xy , unsigned int coproc_type ) === This function releases the lock granting exclusive access to the coprocessor identified by the and arguments, after coprocessor and channels deactivation. === 3) void '''giet_coproc_channel_init'''( unsigned int cluster_xy , unsigned int coproc_type , unsigned int channel , giet_coproc_channel_t* desc ) === This function initializes a TO_COPROC/FROM_COPROC communication channel for the coprocessor identified by the and arguments. The argument define the channel index (TO_COPROC channels use the smallest indexes). The argument is a pointer on the structure containing the channel parameters ( actually defined in the [source:soft/giet_vm/giet_libs/stdio.h stdio.h] file). {{{ typedef struct giet_coproc_channel { unsigned int channel_mode; // MWMR / DMA_IRQ / DMA_NO_IRQ unsigned int buffer_size; // memory buffer size unsigned int buffer_vaddr; // memory buffer virtual address unsigned int status_vaddr; // MWMR status virtual address (for MWMR mode only) unsigned int lock_vaddr; // MWMR lock virtual address (for MWMR mode only) } giet_coproc_channel_t; }}} '''NOTE''' : The field define the virtual address of the MWMR channel status, that is an array of 3 uint32_t words (STS / PTR / PTW) as in the mwmr_channel_t structure defined in the mwmr_channel.h file. The define the virtual address of the queuing user_lock_t structure defined in the user_lock.h file. === 4) void '''giet_coproc_run'''( unsigned int cluster_xy , unsigned int coproc_type ) === This function activates all communication channels and the allocated coprocessor itself in the cluster identified by the arguments. The calling thread exit if the coprocessor does not exist. === 5) void '''giet_coproc_completed'''( unsigned int cluster_xy , unsigned int coproc_type ) === This blocking function can be used to synchronize a software thread with an hardware coprocessor identified by the and arguments, and running in DMA_NO_IRQ mode. It polls the status register of all communication channels, and returns only when all transfers are completed. The calling thread exit when at least one channel status register indicates a bus error (illegal memory access). == __TTY related system calls__ == The GIET_VM allows an user thread to use a private TTY terminal, or to display log message on the kernel TTY0 terminal. === 1) void '''giet_tty_alloc'''( unsigned int shared ) === If the '''shared''' argument has a zero value, this function allocates a private terminal : the TTY terminal index is registered only in the calling thread context. If the '''shared''' argument has a non-zero value, it allocate a shared terminal : the same TTY terminal index is registered in the thread context of all threads that are in the same vspace as the calling thread. The calling thread exit if no TTY terminal available. WARNING: A shared TTY should be protected by an user-level lock. === 2) void '''giet_tty_printf'''( char* format, ... ) === This function print formated text on a private terminal that must have been allocated to the calling thread by the ''get_tty_alloc()'' function. Therefore, it does not take any lock, but checks terminal allocation. Only a limited number of formats are supported: * %d : signed decimal * %u : unsigned decimal * %x : 32 bits hexadecimal * %l : 64 bits hexadecimal * %c : char * %s : string thread exit if private terminal index not defined, or in case of illegal format. === 3) void '''giet_tty_getc'''( char* byte ) === This blocking function fetches a single character from the private terminal that must have been previously allocated to the calling thread. It uses the TTY_RX_IRQ interrupt, and the associated kernel buffer. The thread exit if a threadprivate TTY index not defined. === 4) void '''giet_tty_getw'''( unsigned int* val ) === This blocking function fetches a string of decimal characters (most significant digit first) to build a 32-bits unsigned integer from the private TTY terminal that must have been allocated to the calling thread. It uses the TTY_RX_IRQ interrupt, and the associated kernel buffer. The non-blocking system function _tty_read is called several times, and the decimal characters are written in a 32 characters buffer until a character is read. It ignores non-decimal characters, and displays an echo for each decimal character. The character is interpreted, and previous characters can be cancelled. When the character is received, the string is converted to an unsigned int value. If the number of decimal digit is too large for the 32 bits range, the zero value is returned. The thread threadexit if private TTY index not defined. === 5) void '''giet_tty_gets'''( char* buf, unsigned int bufsize ) === This blocking function fetches a string from the private terminal that must have been allocated to the calling thread. It writes the string to a fixed length buffer. It uses the TTY_RX_IRQ interrupt, and the associated kernel buffer. Up to (bufsize - 1) characters (including the non printable characters) are copied into buffer, and the string is completed by a NUL character. The character is interpreted, and the function close the string with a NUL character if is read. The character is interpreted, and the corresponding character(s) are removed from the target buffer. It does not provide an echo. The thread exit if a private TTY index is threadnot defined. == __Timer related system calls__ == The GIET_VM allows an user thread to activate a private timer channel, generating periodical IRQs. This timer is allocated in the external multi-timers peripheral. === 1) void '''giet_timer_alloc'''() This function allocates a private user timer to the calling thread, and registers the channel index in the thread context. The thread exit if no timer channel is available === 2) void '''giet_timer_start'''( unsigned int period ) This function starts the private timer allocated to the calling thread. The thread exit if no channel is allocated to the calling thread. === 3) void '''giet_timer_stop'''( ) === This function stops the private timer allocated to the calling thread. The thread exit if no channel is allocated to the calling thread. == __File system related system calls__ == The Giet-VM supports a FAT32 file system, and uses distributed data structures to access the file system: * The Inode-Tree (distributed on all clusters) is the internal representation of the File System tree. * The Fat-Cache (distributed on all clusters) is used to cache the FAT region of the block device. * The File-Cache (distributed on all clusters / one cache per open file) is used to cache the DATA region of the block device. * The File-Descriptor-Array (in cluster[0,0]) contains the open files descriptors. * The Fat-Descriptor (in cluster[0,0] contains the FAT32 general information. The error code map (negative values) is defined in the [source:soft/giet_vm/giet_fat32/fat32_shared.h fat32_shared.h] file. === 1) int '''giet_fat_open'''( char* pathname, unsigned int flags ) === This function allocates a file descriptor to the calling thread, for the file identified by its absolute . If several threads try to open the same file, each thread obtains a private file descriptor. The semantic is similar to the UNIX open() function, but the UNIX access rights are not supported. The following flags are supported, and can be ''ored'' to define the argument: * O_RDONLY : The file can only be accessed for read. * O_WRONLY : The file can only be accessed for write. * O_RDWR : The file can be accessed for read or write. This the default value. * O_CREATE : The file is created if it does not exist on disk. Default is no creation. * O_TRUNC : All clusters allocated to the file are released, and the file size is reset to 0. * O_APPEND : The offset in the file descriptor is initialized to the file size. Default offset value is 0. If one of the directories specified in the paththnamr does not exist, an error is returned. WARNING : A single node name (file or directory) cannot be larger than 33 characters. Returns file descriptor index if success. Returns a negative value if error. === 2) int '''giet_fat_close'''( unsigned int fd_id ) === Close a file identified by the ''fd_id'' file descriptor. It decrements the reference count in the inode associated to the file, and release the fd_id entry in the file descriptors array. If the reference count is zero, it writes all dirty clusters on block device, and releases the memory allocated to the file_cache. Returns 0 if success. Returns a negative value if error. === 3) int '''get_fat_file_info'''( unsigned int fd_id , unsigned int* size , unsigned int* offset ) === This function returns the "size" and the current "offset" value for a file identified by the "fd_id" argument. Returns 0 if success. Returns a negative value if error. === 4) int '''giet_fat_read'''( unsigned int fd_id , void* buffer , unsigned int count ) === This function has the same semantic as the UNIX read() function. It transfers up to bytes from the kernel File_Cache associated to the file identified by , to the user , starting from the current file offset. The number of bytes actually transferred can be smaller than the argument if an EOF is encountered. The offset value is incremented by the number to bytes actually transferred. In case of miss in the File_Cache, it loads all involved clusters into cache. Returns number of bytes actually transferred if success. Returns 0 if (offset + count) is larger than the file size. Returns a negative value if error. === 5) int '''giet_fat_pread'''( unsigned int fd_id , void* buffer , unsigned int count , unsigned int offset ) === This function has the same semantic as the UNIX pread() function. It transfers bytes from the kernel File_Cache associated to the file identified by , to the user , starting from the argument. The ''offset'' field in the file descriptor is not modified. In case of miss in the File_Cache, it loads all involved clusters into cache. Returns number of bytes actually transferred if success. Returns 0 if (offset + count) is larger than the file size. Returns a negative value if error. === 6) int '''giet_fat_write'''( unsigned int fd_id , void* buffer, unsigned int count ) === This function has the same semantic as the UNIX function. It transfers bytes from the user to the kernel File_Cache associated to the file identified by , starting from the current file offset. The offset value is incremented by count. It increases the file size and allocate new clusters if (count + offset) is larger than the current file size. Then it loads and updates all involved clusters in the cache. The FAT region on block device is updated if new clusters are allocated, but the block device DATA region is NOT updated. Returns number of bytes actually transferred if success. Returns a negative value if error. === 7) int '''giet_fat_lseek'''( unsigned int fd_id , unsigned int offset , unsigned int whence ) === This function has the same semantic as the UNIX lseek() function. It repositions the offset in the file descriptor , according to the and arguments. The two accepted values for the whence argument are * SEEK_SET : new_offset <= offset * SEEK_CUR : new_offset <= current_offset + offset * SEEK_END : new_offset <= file_size + offset Returns new offset value (bytes) if success. Returns a negative value if error. === 8) int '''giet_fat_remove'''( char* pathname , unsigned int should_be_dir ) === This function has the same semantic as the UNIX unlink() function. It deletes a file identified by the absolute "pathname" argument from the sile system. An error is reported if the references count (number of open file descriptor) is not zero. All clusters allocated to this file in the block device DATA region are released. The Inode-Tree is updated. the Fat-Cache is updated, and the FAT region is updated on the block device. The memory allocated for the associated File_Cache is released. Returns 0 if success. Returns a negative value if error. === 9) int '''get_fat_rename'''( char* old_path , char* new_path )=== This function has the same semantic as the UNIX rename() function. It causes the node identified by to be renamed as . If exists, it is first removed. Both and must be of the same type (either directories or non directories). Returns 0 if success. Returns a negative value if error. === 10) int '''giet_fat_mkdir'''( char* pathname ) === This function has the same semantic as the UNIX mkdir() function. It creates in the file system the directory specified by the absolute "pathname" argument. The Inode-Tree is updated. One cluster is allocated to the new directory, containing the "." and ".." entries. The associated File-Cache is created. The Fat-Cache is updated, and the FAT region on block device is updated. The DATA region on block device is updated. Returns 0 if success. Returns a negative value if error. === 11) int '''giet_fat_opendir'''( char* pathname ) === This function allocates a file descriptor to the calling thread, for the directory identified by its absolute . Returns the file descriptor associated to the diredtory if success. Returns a negative value if error. === 12) int '''giet_fat_closedir'''( unsigned int fd_id ) === Close a directory identified by the file descriptor. It decrements the reference count in the inode associated to the directory, and release the fd_id entry in the file descriptors array. Returns 0 if success. Returns a negative value if error. === 13) int '''giet_fat_readdir'''( unsigned int fd_id , fat_dirent_t* entry ) === This function access one directory entry identified by the argument (obtained by the giet_fat_opendir() function), and writes the relevant informations to the argument. This includes the cluster, size, is_dir, and name. Returns 0 if success. Returns a negative value if error. === 14) int '''giet_fat_fprintf'''( unsigned int fd_id , char* format , ... ) === This function has the same semantic as the UNIX function. It transfers all bytes contained in the string defined by the argument to the kernel File_Cache associated to the file identified by , starting from the current file offset. The offset value is incremented by the string length. It increases the file size and allocate new clusters if (count + offset) is larger than the current file size. Then it loads and updates all involved clusters in the cache. The FAT region on block device is updated if new clusters are allocated, but the block device DATA region is NOT updated. Returns number of bytes actually transferred if success. Returns a negative value if error. === 15) '''void* giet_fat_mmap'''( void* vaddr , unsigned int length , unsigned int prot , unsigned int flags , unsigned int fd_id , unsigned int offset ) === This function has the same semantic as the UNIX function. It allocates as many small pages (4 Kbytes) as required by the number of bytes defined by the argument, from the MMAP vseg of the calling vspace. It maps all these pages directly to the file_cache as defined by the and arguments. The supported values for the argument are : MAP_PROT_READ / MAP_PROT_WRITE / MAP_PROT_EXEC (can be ored). It has the following limitations: * it does not support the MAP_PRIVATE flag : write are seen by any thread in any application. * it does not support the MAP_FIXED flag : the argument is not used. * it does not support the MAP_ANONYMOUS flog : only file mapping. * The only supported value for the argument is MAP_SHARED. * The and arguments must be multiple of 4 Kbytes. Returns a pointer on the allocated buffer in user space (from the MMAP space). Returns NULL in case of error (illegal arguments). === 16) '''int giet_fat_munmap'''( void* vaddr , unsigned int length ) === This function has the same semantic as the UNIX function. It desallocates as many small pages (4 Kbytes) as defined by the and arguments from the MMAP vseg of the calling space. The dirty pages will be written on disk when the mapped file is closed. It has the following limitations: * The argument must be in the MMAP vseg. * The argument must be multiple of 4 Kbytes. Returns 0 in case of success. Returns -1 in case of error (illegal arguments). == __Network related system call__ == The GIET_VM allows a user application to get and use a private NIC channel, using the CMA component (chained buffers DMA) to transfer packets to or an user buffer. The NIC channel and the CMA channel are registered in the threads contexts. === 1) void '''giet_nic_tx_alloc'''( unsigned int xmax, unsigned int ymax) === This function must be called by one single thread (typically the main() ). It allocates a private NIC_TX channel (coming with the associated kernel NIC_TX chbuf), and a private CMA_TX channel to an application. It registers these NIC_TX and CMA_TX channels in the contexts of all threads that are in the same vspace as the calling thread. These NIC and CMA channels are therefore shared by all thread of a multi-threads application. The packets are transfered by the hardware to the NIC from a distributed kernel chbuf (one 4 Kbytes container per cluster), where the number of involved clusters is defined by the & arguments. The (xmax / ymax) arguments cannot be larger than (X_SIZE / Y_SIZE) defining the max number of clusters in the platform, but they can be smaller. The calling thread exit if no available NIC_TX channel, if no available CMA channel, if (xmax / ymax) are too large, or if there is not enough memory for the distributed kernel containers in one selected cluster. === 2) void '''giet_nic_rx_alloc'''( unsigned int xmax, unsigned int ymax ) === This function must be called by one single thread (typically the main() ). It allocates a private NIC_RX channel (coming with the associated kernel NIC_RX chbuf), and a private CMA channel to an application. It registers these NIC_RX and CMA_RX channels in the contexts of all threads that are in the same space as the calling thread. These NIC and CMA channels are therefore shared by all threads of a multi-threads application. The packets are transfered by the hardware from the NIC to a distributed kernel chbuf (one 4 Kbytes container per cluster), where the number of involved clusters is defined by the & argumentss. The (xmax / ymax) arguments cannot be larger than (X_SIZE / Y_SIZE) defining the max number of clusters in the platform, but they can be smaller. The calling thread exit if no available NIC_TX channel, if no available CMA channel, if (xmax / ymax) are too large, or if there is not enough memory for the distributed kernel containers in one selected cluster. === 3) void '''giet_nic_tx_start'''( ) === This function must be called by one single thread (typically the main() ). It activates both the NIC_TX channel, and the CMA_TX channel allocated to an application, to start the transfer of packets from the distributed kernel chbuf to the NIC. The calling thread exit if no allocated NIC_TX channel or no allocated CMA_TX channel. === 4) void '''giet_nic_rx_start'''( ) === This function must be called by one single thread (typically the main() ). It activates both the NIC_RX channel, and the CMA_RX channel allocated to an application, to start the transfer of packets from the NIC to the distributed kernel chbuf. The calling thread exit if no allocated NIC_RX channel or no allocated CMA_RX channel. === 5) void '''giet_nic_tx_move'''( void* buffer ) === This blocking function transfer one container (4 Kbytes) from an user buffer to the kernel chbuf defined by the NIC_TX channel registered in the calling thread context. The argument is the container base address in user space. Several user threads can concurrently access the same chbuf, because the syscall handler takes the lock protecting the chbuf. It returns only when the container has been fully transfered. The calling thread exit if the buffer is not in user space, or if no allocated NIC_TX channel, or in case of timeout. === 6) void '''giet_nic_rx_move'''( void* buffer ) === This blocking function transfer one container (4 Kbytes) from the kernel chbuf defined by the NIC_TX channel registered in the calling thread context to an user buffer. The argument is the container base address in user space. Several user threads can concurrently access the same chbuf, because the syscall handler takes the lock protecting the chbuf. It returns only when the container has been fully transfered. The calling thread exit if the buffer is not in user space, or if no allocated NIC_RX channel, or in case of timeout. === 7) void '''giet_nic_tx_stop'''( ) === This function must be called by one single thread (typically the main() ). It desactivates both the NIC_TX channel and the CMA_TX channel allocated to the calling thread. The calling thread exit if no allocated NIC_TX channel or no allocated CMA_TX channel. === 8) void '''giet_nic_rx_stop'''( ) === This function must be called by one single thread (typically the main() ). It desactivates both the NIC_RX channel and the CMA channel allocated to the calling thread. The calling thread exit if no allocated NIC_RX channel or no allocated CMA channel. === 9) void '''giet_nic_rx_clear'''( ) === This function reset all instrumentation (packets counters) associated to the RX channels. === 10) void '''giet_nic_tx_clear'''( ) === This function reset all instrumentation (packets counters) associated to the TX channels. === 11) void '''giet_nic_rx_stats'''( ) === This function display on kernel TTY0 the content of the instrumentation registers associated to the RX channels. === 12) void '''giet_nic_tx_stats'''( ) === This function display on kernel TTY0 the content of the instrumentation registers associated to the TX channels. == __Frame Buffer related system calls__ == To display images, an user application must get the frame buffer ownership, and check the frame buffer size (width and height). Then, it can access the frame buffer through a (software) memcpy() or through the (hardware) ''Chained Buffer DMA'' controller (called CMA). === 1) void '''giet_fbf_size'''( unsigned int* width , unsigned int* height) === This function returns in the and arguments the number of pixels per line, and the number of lines of the frame buffer === 2) void '''giet_fbf_alloc'''() === This blocking function allows an application to get exclusive ownership of the shared FBF peripheral. It returns only when the lock has been taken. All threads in the same space as the calling thread can access concurrently the frame buffer, under the user responsibility. This lock is released only when when all threads in the application complete execution, after a giet_pthread_exit(), or a giet_pthread_kill(). === 3) void '''giet_fbf_cma_alloc'''( unsigned int nbufs ) This function allocates a CMA channel to an application, and registers the channel index in the contexts of all threads that are in the same space as the calling thread. The argument define the total number of chained user buffers. As each user buffer contains one image, the buffer size must be FBUF_X_SIZE * FBUF_Y_SIZE. The user buffers can be distributed (one buffer per cluster) or not (all buffers in same cluster). This function initializes the chained buffer descriptor for the frame buffer (one single buffer). The thread exit if no CMA channel available. === 4) void '''giet_fbf_cma_init_buf'''( unsigned int index void* buf_vaddr , void* sts_vaddr ) === This function initializes the chained buffer descriptor for one user buffer identified by the argument. The and arguments are pointers on the buffer and on the buffer status. This argument must be smaller than the argument in giet_fbf_cma_alloc() above. The set of user buffers will be transferred by the CMA peripheral in the order of increasing indexes. This function must be called times, to initialize the chained buffers descriptors. Each user buffer must be large enough to store a complete image, and must be aligned on a 64 bytes boundary. The buffer status contain just a Boolean, but it must occupy 64 bytes, and must be aligned on a 64 bytes boundary. For a given user buffer, the buffer and the associated status must be in the same cluster. The thread exit if buffers are not aligned, index too large, or buffer and status in different clusters. === 5) void '''giet_fbf_cma_start'''() === This function activates the transfer of a stream of images from a set of chained user buffers to the frame buffer. It must be used in conjunction with the giet_fbf_cma_display() function. The chained buffer descriptors should have been initialized by the giet_fbf_cma_init_buf() function. === 6) void '''giet_fbf_cma_check'''( unsigned int index ) === For each user buffer, the status is acting as a SET/RESET synchronisation flip-flop, that is set by the application when the buffer is full, and is reset by the CMA peripheral when the transfer is completed. This blocking function checks the status of the buffer identified by the argument, and returns only when the buffer is empty. === 7) void '''giet_fbf_cma_display'''( unsigned int index ) === For each user buffer, the status is acting as a SET/RESET synchronisation flip-flop, that is set by the application when the buffer is full, and is reset by the CMA peripheral when the transfer is completed. This function set the status to enable the transfer of the buffer identified by the argument. === 8) void '''giet_fbf_cma_stop'''( ) === This function desactivates the CMA channel allocated to the calling thread. === 9) void '''giet_fbf_sync_read'''( unsigned int offset , void* buffer , unsigned int length ) === This blocking function use a memcopy strategy to transfer data from the frame buffer to an user buffer. * '''offset''' defines the offset (in bytes) in the frame buffer, * '''buffer''' is the user buffer base address, * '''length''' is the number of bytes to be transfered. === 10) void '''giet_fbf_sync_write'''( unsigned int offset , void* buffer , unsigned int length ) === This blocking function use a memcopy strategy to transfer data from an user buffer to the frame buffer. * '''offset''' defines the offset (in bytes) in the frame buffer, * '''buffer''' is the user buffer base address, * '''length''' is the number of bytes to be transfered. == __Miscelaneous system calls__ == === 1) void '''giet_procs_number'''( unsigned int* x_size , unsigned int* y_size , unsigned int* nprocs ) === This function returns the actual number of processors in a clusterized 2D mesh architecture. The argument is the number of clusters containing processors in a row. The argument is the number of clusters containing processors in a column. The argument is the number of processors per cluster. === 2) void '''giet_vseg_get_vbase'''( char* vspace_name, char* vseg_name, unsigned int* vbase) === This function returns in the argument the virtual base address of a vseg defined in the mapping_info data structure. The vseg is identified by the and arguments. In case of error (such as undefined vspace or undefined vseg), the calling thread exit. === 3) void '''giet_vseg_get_length'''( char* vspace_name, char* vseg_name, unsigned int* length) === This function returns in the argument the length (bytes) of a vseg defined in the mapping_info data structure. The vseg is identified by the and . In case of error (such as undefined vspace or undefined vseg), the calling thread exit. === 4) void '''giet_heap_info'''( unsigned int* vaddr, unsigned int* length, unsigned int x, unsigned int y ); This function returns in the and arguments the characteristics of the user heap located in cluster[x,y] and defined in the space running the calling thread. In case of error (such as undefined heap segment in the selected cluster, or illegal cluster coordinates) it returns = = 0. === 5) void '''giet_get_xy'''( void* ptr, unsigned int* px, unsigned int* py ) === This function returns through the and arguments the coordinates of the cluster containing the physical address associated to the argument containing a virtual address. In case of error (unmapped virtual address), the calling thread exit.