AX_HAVE_EPOLL([ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND]) AX_HAVE_EPOLL_PWAIT([ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])
This macro determines whether the system supports the epoll I/O event interface. A neat usage example would be:
AX_HAVE_EPOLL(
[AX_CONFIG_FEATURE_ENABLE(epoll)],
[AX_CONFIG_FEATURE_DISABLE(epoll)])
AX_CONFIG_FEATURE(
[epoll], [This platform supports epoll(7)],
[HAVE_EPOLL], [This platform supports epoll(7).])
The epoll interface was added to the Linux kernel in version 2.5.45, and the macro verifies that a kernel newer than this is installed. This check is somewhat unreliable if <linux/version.h> doesn’t match the running kernel, but it is necessary regardless, because glibc comes with stubs for the epoll_create(), epoll_wait(), etc. that allow programs to compile and link even if the kernel is too old; the problem would then be detected only at runtime.
Linux kernel version 2.6.19 adds the epoll_pwait() call in addition to epoll_wait(). The availability of that function can be tested with the second macro. Generally speaking, it is safe to assume that AX_HAVE_EPOLL would succeed if AX_HAVE_EPOLL_PWAIT has, but not the other way round.
Download the latest version of ax_have_epoll.m4 or browse the macro’s revision history.
Copyright © 2008 Peter Simons simons@cryp.to
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