diff options
-rw-r--r-- | nuttx/TODO | 113 | ||||
-rw-r--r-- | nuttx/drivers/mmcsd/mmcsd_spi.c | 4 |
2 files changed, 113 insertions, 4 deletions
diff --git a/nuttx/TODO b/nuttx/TODO index 28bd90e84..eb432d96e 100644 --- a/nuttx/TODO +++ b/nuttx/TODO @@ -1,4 +1,4 @@ -NuttX TODO List (Last updated June 20, 2013) +NuttX TODO List (Last updated June 23, 2013) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ This file summarizes known NuttX bugs, limitations, inconsistencies with @@ -13,7 +13,7 @@ nuttx/ (3) Signals (sched/, arch/) (2) pthreads (sched/) (8) Kernel Build - (2) C++ Support + (4) C++ Support (6) Binary loaders (binfmt/) (16) Network (net/, drivers/net) (4) USB (drivers/usbdev, drivers/usbhost) @@ -512,6 +512,115 @@ o C++ Support constructor logic will probably have to be performed by user logic in user_start(). + Title: STATIC CONSTRUCTORS AND MULTITASKING + Description: The logic that calls static constructors operates on the main + thread of the initial user application task. Any static + constructors that cache task/thread specific information such + as C streams or file descriptors will not work in other tasks. + See also UCLIBC++ AND STATIC CONSTRUCTORS below. + Status: Open + Priority: Low and probably will not changed. In these case, there will + need to be an application specific solution. + + Title: UCLIBC++ AND STATIC CONSTRUCTORS + uClibc++ was designed to work in a Unix environment with + processes and with separately linked executables. Each process + has its own, separate uClibc++ state. uClibc++ would be + instantiated like this in Linux: + + 1) When the program is built, a tiny start-up function is + included at the beginning of the program. Each program has + its own, separate list of C++ constructors. + + 2) When the program is loaded into memory, space is set aside + for uClibc's static objects and then this special start-up + routine is called. It initializes the C library, calls all + of the constructors, and calls atexit() so that the destructors + will be called when the process exits. + + In this way, you get a per-process uClibc++ state since there + is per-process storage of uClibc++ global state and per-process + initialization of uClibc++ state. + + Compare this to how NuttX (and most embedded RTOSs) would work: + + 1) The entire FLASH image is built as one big blob. All of the + constructors are lumped together and all called together at + one time. + + This, of course, does not have to be so. We could segregate + constructors by some criteria and we could use a task start + up routine to call constructors separately. We could even + use ELF executables that are separately linked and already + have their constructors separately called when the ELF + executable starts. + + But this would not do you very much good in the case of + uClibc++ because: + + 2) NuttX does not support processes, i.e., separate address + environments for each task. As a result, the scope of global + data is all tasks. Any change to the global state made by + one task can effect another task. There can only one + uClibc++ state and it will be shared by all tasks. uClibc++ + apparently relies on global instances (at least for cin and + cout) there is no way to to have any unique state for any + "task group". + + [NuttX does not support processes because in order to have + true processes, your hardware must support a memory management + unit (MMU) and I am not aware of any mainstream MCU that has + an MMU (or, at least an MMU that is capable enough to support + processes).] + + NuttX does not have processes, but it does have "task groups". + See http://www.nuttx.org/doku.php?id=wiki:nxinternal:tasksnthreads. + A task group is the task plus all of the pthreads created by + the task via pthread_create(). Resources like FILE streams + are shared within a task group. Task groups are like a poor + man's process. + + This means that if the uClibc++ static classes are initialized + by one member of a task group, then cin/cout should work + correctly with all threads that are members of task group. The + destructors would be called when the final member of the task + group exists (if registered via atexit()). + + So if you use only pthreads, uClibc++ should work very much like + it does in Linux. If your NuttX usage model is like one process + with many threads then you have Linux compatibility. + + If you wanted to have uClibc++ work across task groups, then + uClibc++ and NuttX would need some extensions. I am thinking + along the lines of the following: + + 1) There is a per-task group storage are withing the RTOS (see + include/nuttx/sched.h). If we add some new, nonstandard APIs + then uClibc++ could get access to per-task group storage (in + the spirit of pthread_getspecific() which gives you access to + per-thread storage). + + 2) Then move all of uClibc++'s global state into per-task group + storage and add a uClibc++ initialization function that would: + a) allocate per-task group storage, b) call all of the static + constructors, and c) register with atexit() to perform clean- + up when the task group exits. + + That would be a fair amount of effort. I don't really know what + the scope of such an effort would be. I suspect that it is not + large but probably complex. + + NOTES: + + 1) See STATIC CONSTRUCTORS AND MULTITASKING + + 2) To my knowledge, only some uClibc++ ofstream logic is + sensitive to this. All other statically initialized classes + seem to work OK across different task groups. + Status: Open + Priority: Low. I have no plan to change this logic now unless there is + some strong demand to do so. + o Binary loaders (binfmt/) ^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/nuttx/drivers/mmcsd/mmcsd_spi.c b/nuttx/drivers/mmcsd/mmcsd_spi.c index bb026954d..be4ebdcdc 100644 --- a/nuttx/drivers/mmcsd/mmcsd_spi.c +++ b/nuttx/drivers/mmcsd/mmcsd_spi.c @@ -365,8 +365,8 @@ static void mmcsd_semtake(FAR struct mmcsd_slot_s *slot) */ SPI_SETFREQUENCY(slot->spi, slot->spispeed); - SPI_SETMODE(slot->sp, CONFIG_MMCSD_SPIMODE); - SPI_SETBITS(slot->sp, 8); + SPI_SETMODE(slot->spi, CONFIG_MMCSD_SPIMODE); + SPI_SETBITS(slot->spi, 8); #endif /* Get exclusive access to the MMC/SD device (prossibly un-necessary if |