diff --git a/Documentation/NuttX.html b/Documentation/NuttX.html index 3b962c3996..760d49e6df 100644 --- a/Documentation/NuttX.html +++ b/Documentation/NuttX.html @@ -8,7 +8,7 @@
Last Updated: March 22, 2012
+Last Updated: March 24, 2012
+
Last Updated: March 22, 2012
+Last Updated: March 24, 2012
Note: Many of the fundamental classed in NxWidgets derive from the Antony diff --git a/TODO b/TODO index f5dd64ddf0..85c1936b9d 100644 --- a/TODO +++ b/TODO @@ -84,6 +84,8 @@ o Task/Scheduler (sched/) Title: MISSING ERRNO SETTINGS Description: Several APIs do not set errno. Need to review all APIs. + Update: These are being fixed as they are encountered. There is + no accounting of how many interfaces have this problem. Status: Open Priority: Medium, required for standard compliance (but makes the code bigger) @@ -208,7 +210,45 @@ o pthreads (sched/) being moved to the tail of the scheduling queue at its priority in the event that its original priority is changed." Status: Open - Priority: Low, probably not that useful + Priority: Low -- about zero, probably not that useful. Priority inheritance is + already supported and is a much better solution. And it turns out + that priority protection is just about as complex as priority inheritance. + Exerpted from my post in a Linked-In discussion: + + "I started to implement this HLS/"PCP" semaphore in an RTOS that I + work with (http://www.nuttx.org) and I discovered after doing the + analysis and basic code framework that a complete solution for the + case of a counting semaphore is still quite complex -- essentially + as complex as is priority inheritance. + + "For example, suppose that a thread takes 3 different HLS semaphores + A, B, and C. Suppose that they are prioritized in that order with + A the lowest and C the highest. Suppose the thread takes 5 counts + from A, 3 counts from B, and 2 counts from C. What priority should + it run at? It would have to run at the priority of the highest + priority semaphore C. This means that the RTOS must maintain + internal information of the priority of every semaphore held by + the thread. + + "Now suppose it releases one count on semaphore B. How does the + RTOS know that it still holds 2 counts on B? With some complex + internal data structure. The RTOS would have to maintain internal + information about how many counts from each semaphore are held + by each thread. + + "How does the RTOS know that it should not decrement the priority + from the priority of C? Again, only with internal complexity. It + would have to know the priority of every semaphore held by + every thread. + + "Providing the HLS capability on a simple phread mutex would not + be such quite such a complex job if you allow only one mutex per + thread. However, the more general case seems almost as complex + as priority inheritance. I decided that the implementation does + not have value to me. I only wanted it for its reduced + complexity; in all other ways I believe that it is the inferior + solution. So I discarded a few hours of programming. Not a + big loss from the experience I gained." o C++ Support ^^^^^^^^^^^ @@ -231,6 +271,13 @@ o C++ Support Title: STATIC CONSTRUCTORS Description: Need to call static constructors + Update: Static constructors are implemented for the STM32 F4 and + this will provide the model for all solutions. Basically, if + CONFIG_HAVE_CXXINITIALIZE=y is defined in the configuration, then + board-specific code must provide the interface up_cxxinitialize(). + up_cxxinitialize() is called from user_start() to initialize + all static class instances. This TODO item probably has to stay + open because this solution is only available on STM32 F4. Status: Open Priority: Low, depends on toolchain. Call to gcc's built-in static constructor logic will probably have to be performed by @@ -462,7 +509,8 @@ o USB (drivers/usbdev, drivers/usbhost) Title: USB STORAGE DRIVER DELAYS Description: There is a workaround for a bug in drivers/usbdev/usbdev_storage.c. - that involves delays. This needs to be redesigned to eliminate these delays. + that involves delays. This needs to be redesigned to eliminate these + delays. See logic conditioned on CONFIG_USBMSC_RACEWAR. Status: Open Priority: Medium @@ -565,6 +613,7 @@ o File system / Generic drivers (fs/, drivers/) Title: CAN POLL SUPPORT Description: At present, the CAN driver does not support the poll() method. + See drivers/can.c Status: Open Priority: Low @@ -1302,9 +1351,6 @@ o MIPS/PIC32(arch/mips) Status: Open Priority: High - - - o Hitachi/Renesas SH-1 (arch/sh/src/sh1) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^