9b42b85ed8
Since core ABI 21, users can decide whether a new element should be
made public or private depending on the value of clone flags added to
the new long form of all element creation calls, i.e. evl_create_*().
All evl_new_*() calls become a shorthand for their respective long
form with reasonable default arguments, including private visibility.
As a shorthand, libevl also interprets a slash character leading the
name argument passed to these services as an implicit request for
creating a public element. In other words, this is the same as passing
EVL_CLONE_PUBLIC in the clone flags.
A public element appears as a cdev in the /dev/evl hierarchy, which
means that it is visible to other processes, which may share it. On
the contrary, a private element is only known from the process
creating it, although it does appear in the /sysfs hierarchy
regardless.
e.g.:
efd = evl_attach_self("/visible-thread");
total 0
crw-rw---- 1 root root 248, 1 Apr 17 11:59 clone
crw-rw---- 1 root root 246, 0 Apr 17 11:59 visible-thread
or,
efd = evl_attach_self("private-thread");
total 0
crw-rw---- 1 root root 248, 1 Apr 17 11:59 clone
Signed-off-by: Philippe Gerum <rpm@xenomai.org>
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||
|---|---|---|
| .. | ||
| Makefile | ||
| README.md | ||
| clock.c | ||
| event.c | ||
| flags.c | ||
| heap.c | ||
| init.c | ||
| internal.h | ||
| mutex.c | ||
| poll.c | ||
| proxy.c | ||
| sched.c | ||
| sem.c | ||
| thread.c | ||
| timer.c | ||
| version.c | ||
README.md
== PURPOSE of libeshi
The EVL shim library mimics the behavior of the original EVL API based on plain POSIX calls from the native *libc, which does not require the EVL core to be enabled in the host kernel. It is useful when the real-time guarantees delivered by the EVL core are not required for quick prototyping or debugging application code.
== USAGE
To build against the EVL shim library, you need to update a couple of settings from the Makefile building your application as follows (*):
CPPFLAGS/CFLAGS:
- Replace -I$(prefix)/include by -I$(prefix)/include/eshi
LDFLAGS:
- Replace -levl by -leshi
For instance:
(CC) -o app app.c -I(prefix)/include/eshi -L$(prefix)/lib -leshi -lpthread -lrt
(*) $(prefix) is the installation root of libevl (e.g. /usr/evl).
== LIMITATIONS
This API supports process-local services only. The resources/objects it creates cannot be shared between processes.
The following calls are not supported:
evl_peek_flags evl_peek_sem evl_new_xbuf evl_open_mutex evl_open_event evl_open_flags evl_open_sem
== VARIATION(S)
evl_poll: POLLOUT is always set for evl_flags. Unlike with the native libevl API, this condition cannot be monitored for detecting event consumption by the receiver side, i.e. waiting for the value to be cleared upon a successful call to evl_wait*_flags.