Package: asio
Version: 1.3.1-1
Severity: normal
Tags: patch
Hi there,
If libc6-dev supports eventfd (which is the in experimental) but the
buildd's kernel or the developer's kernel doesn't, asio fails to build
in the test suite; see e.g.:
http://launchpadlibrarian.net/20538394/buildlog_ubuntu-jaunty-i386.asio_1.3.1-1_FAILEDTOBUILD.txt.gz
There are actually two problems with this:
1) asio's build will differ depending on the libc6-dev used to build
the package; as some arches lag, or when developers upload binary
packages in general, this might cause surprizes; it would be
reasonnable to force disabling eventfd support for now
(-DASIO_DISABLE_EVENTFD) and revert this while adding a libc6-dev
build-dep when it's available with libc6-dev support on all arches;
this is also useful for e.g. backports. Consider that packages
build-depending on asio will also be able to use this information to
build-dep on an asio with eventfd support reliably.
2) the package actually failing to pass the testsuite in some cases.
I'd recommend detecting eventfd support at runtime in the testsuite
and providing macros to do this for programs using the lib.
3) There's another unrelated problem: eventfd support is assumed
starting with a particular kernel version, but it's configurable and
can be backported to an older kernel as well; asio shouldn't use
kernel versions as proxies, but check at build and runtime for this
support.
For 1), the attached debdiff sets ASIO_DISABLE_EVENTFD in CXXFLAGS
during check and documents this in README.Debian. For 2 and 3), I'd
recommend:
- changing include/asio/detail/select_interrupter.hpp into a real class
which would detect which select_interrupter implementation to use at
runtime
- checking for eventfd in the system headers at build time and using
the result in the installed headers (instead of requiring all users
to test for it)
but it would be too error prone for me to implement the first part and
setting ASIO_DISABLE_EVENTFD is a good workaround in the mean time. :-P
Cheers,
-- System Information:
Debian Release: 5.0
APT prefers unstable
APT policy: (500, 'unstable'), (1, 'experimental')
Architecture: i386 (i686)
Kernel: Linux 2.6.27-1-686 (SMP w/2 CPU cores)
Locale: LANG=fr_FR.UTF-8, LC_CTYPE=fr_FR.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash
--
Loïc Minier
diff -u asio-1.3.1/debian/changelog asio-1.3.1/debian/changelog
--- asio-1.3.1/debian/changelog
+++ asio-1.3.1/debian/changelog
@@ -1,3 +1,14 @@
+asio (1.3.1-1.1) unstable; urgency=low
+
+ * Add a README.Debian to document that building programs using asio against
+ an eventfd-aware libc6-dev will introduce a runtime dependency on a kernel
+ with CONFIG_EVENTFD set.
+ * Define ASIO_DISABLE_EVENTFD in CXXFLAGS when running make check as
+ otherwise it fails to build with recent libc6-dev and older kernel
+ (typical on buildds running stable but building e.g. experimental).
+
+ -- Loic Minier <[email protected]> Sat, 20 Dec 2008 16:09:22 +0100
+
asio (1.3.1-1) unstable; urgency=low
* New upstream release
diff -u asio-1.3.1/debian/rules asio-1.3.1/debian/rules
--- asio-1.3.1/debian/rules
+++ asio-1.3.1/debian/rules
@@ -2,7 +2,7 @@
#export DH_VERBOSE=1
-CXXFLAGS = -W -Wall -g -pipe
+CXXFLAGS = -W -Wall -g -pipe -DASIO_DISABLE_EVENTFD
configure: configure.ac
aclocal-1.10
only in patch2:
unchanged:
--- asio-1.3.1.orig/debian/README.Debian
+++ asio-1.3.1/debian/README.Debian
@@ -0,0 +1,12 @@
+eventfd() support
+=================
+
+The current asio headers will turn on eventfd support at build time if
+your libc6-dev supports it, disregarding support in the runtime kernel.
+
+In other words, if you build programs using asio against a recent libc6-dev,
+they require a kernel with CONFIG_EVENTFD to run. You can define
+ASIO_DISABLE_EVENTFD via CXXFLAGS to forcibly disable eventfd support.
+
+eventfd was included in linux 2.6.22.
+
