mirror of
https://github.com/apache/nuttx.git
synced 2026-06-07 17:33:08 +08:00
Gregory Nutt
67ec3d7926
This commit resolves issue #620: Remove CONFIG_CAN_PASS_STRUCTS #620 The configuration option CONFIG_CAN_PASS_STRUCTS was added many years ago to support an old version of the SDCC compiler. That compiler is currently used only with the Z80 and Z180 targets. The limitation of that old compiler was that it could not pass structures or unions as either inputs or outputs. For example: #ifdef CONFIG_CAN_PASS_STRUCTS struct mallinfo mallinfo(void); #else int mallinfo(FAR struct mallinfo *info); #endif And even leads to violation of a few POSIX interfaces like: #ifdef CONFIG_CAN_PASS_STRUCTS int sigqueue(int pid, int signo, union sigval value); #else int sigqueue(int pid, int signo, FAR void *sival_ptr); #endif This breaks the 1st INVIOLABLES rule: Strict POSIX compliance ----------------------- o Strict conformance to the portable standard OS interface as defined at OpenGroup.org. o A deeply embedded system requires some special support. Special support must be minimized. o The portable interface must never be compromised only for the sake of expediency. o Expediency or even improved performance are not justifications for violation of the strict POSIX interface Also, it appears that the current SDCC compilers have resolve this issue and so, perhaps, this is no longer a problem: z88dk/z88dk#1132 NOTE: This commit cannot pass the PR checks because it depends on matching changes to the apps/ directory.
README ====== This directory holds NuttX libraries. Libraries in NuttX are very special creatures. They have these properties: 1. They can be shared by both application logic and logic within the OS when using the FLAT build. 2. But in PROTECTED and KERNEL modes, they must be built differently: The copies used by applications and the OS cannot be the same. Rather, separate versions of libraries must be built for the kernel and for applications. 3. When used by the OS, some special care must be taken to assure that the OS logic does not disrupt the user's errno value and that the OS does not create inappropriate cancellation points. For example, sem_wait() is both a cancellation point and modifies the errno value. So within the FLAT build and without kernel version for the PROTECTED and KERNEL builds, the special internal OS interface nxsem_wait() must be used. Within libraries, the macro _SEM_WAIT() (as defined in include/nuttx/semaphore.h) is used instead. The definition of this macro accounts for the different usage environments. NOTE: The libraries under libs/ build differently from other NuttX components: There are no build-related files in the libs/ directory; it is simply a container for other well-known, individual library directories. The upper level Makefile logic is aware of the libraries within the libs/ container. The only real function of the libs/ directory is to prevent the top-level directory from becoming cluttered with individual libraries.