Kay Sievers
5d6a1fa6e9
On Fri, Nov 7, 2008 at 13:07, Matthias Schwarzott <zzam@gentoo.org> wrote: > I managed to let udev-131 segfault at startup. > > I configured it like this: > CFLAGS="-Wall -ggdb" ./configure --prefix=/usr --sysconfdir=/etc --exec-prefix= > > Running it in gdb shows it segfaults at udev-rules.c:831 > > (gdb) run > Starting program: /tmp/udev-131/udev/udevd > > Program received signal SIGSEGV, Segmentation fault. > 0x0804ea06 in get_key (udev=0x9175008, line=0xafcdc8f0, key=0xafcdc5d8, > op=0xafcdc5d0, value=0xafcdc5d4) > at udev-rules.c:831 > 831 dbg(udev, "%s '%s'-'%s'\n", operation_str[*op], *key, *value); If compiled without optimization, the dbg() macro dereferences variables which are not available. Convert the string array to a function, which just returns NULL if compiled without DEBUG.
udev - userspace device management
For more information see the files in the docs/ directory.
Important Note:
Integrating udev in the system has complex dependencies and differs from distro
to distro. All major distros depend on udev these days and the system may not
work without a properly installed version. The upstream udev project does not
recommend to replace a distro's udev installation with the upstream version.
Requirements:
- Version 2.6.19 of the Linux kernel for reliable operation of this release of
udev. The kernel may have a requirement on udev too, see Documentation/Changes
in the kernel source tree for the actual dependency.
- The kernel must have sysfs, unix domain sockets and networking enabled.
(unix domain sockets (CONFIG_UNIX) as a loadable kernel module may work,
but it does not make any sense - don't complain if anything goes wrong.)
- The proc filesystem must be mounted on /proc/, the sysfs filesystem must
be mounted at /sys/. No other locations are supported by udev.
Operation:
Udev creates and removes device nodes in /dev/, based on events the kernel
sends out on device discovery or removal.
- Very early in the boot process, the /dev/ directory should get a 'tmpfs'
filesystem mounted, which is populated from scratch by udev. Created nodes
or changed permissions will not survive a reboot, which is intentional.
- The content of /lib/udev/devices/ directory which contains the nodes,
symlinks and directories, which are always expected to be in /dev, should
be copied over to the tmpfs mounted /dev, to provide the required nodes
to initialize udev and continue booting.
- The old hotplug helper /sbin/hotplug should be disabled on bootup, before
actions like loading kernel modules are taken, which may cause a lot of
events.
- The udevd daemon must be started on bootup to receive netlink uevents
from the kernel driver core.
- All kernel events are matched against a set of specified rules in
/lib/udev/rules.d/ which make it possible to hook into the event
processing to load required kernel modules and setup devices. For all
devices the kernel exports a major/minor number, udev will create a
device node with the default kernel name, or the one specified by a
matching udev rule.
Please direct any comment/question/concern to the linux-hotplug mailing list at:
linux-hotplug@vger.kernel.org