On Wed, 2020-04-15 at 17:10 +0200, Ján Tomko wrote:
Migrate the following wiki articles: https://wiki.libvirt.org/page/DebugLogs https://wiki.libvirt.org/page/Debugging
With the syntax changed to rST and rewrapped.
Signed-off-by: Ján Tomko <jtomko@redhat.com> --- I might've changed an article or two, too. Or rather: the article 'the'.
docs/kbase.html.in | 3 + docs/kbase/debugging.rst | 303 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 306 insertions(+) create mode 100644 docs/kbase/debugging.rst
This fails to apply for me: Applying: docs: kbase: add a page about debugging error: corrupt patch at line 335 Patch failed at 0001 docs: kbase: add a page about debugging hint: Use 'git am --show-current-patch' to see the failed patch When you have resolved this problem, run "git am --continue". If you prefer to skip this patch, run "git am --skip" instead. To restore the original branch and stop patching, run "git am --abort". [...]
+++ b/docs/kbase/debugging.rst @@ -0,0 +1,303 @@ +================= +Debugging libvirt +================= + +.. contents:: + + +If you `report a bug <https://libvirt.org/bugs.html>`_ against libvirt, in most
I think we want to make links to other libvirt documentation relative, so that they work correctly even when browsing an offline copy locally. [...]
+The daemon configuration files location is dependent on the `connection URI +<http://libvirt.org/uri.html>`_. For ``qemu:///system``: + +* open ``/etc/libvirt/libvirtd.conf`` in your favourite editor +* find & replace, or set these variables:: + + # LEGACY SETTINGS PRIOR LIBVIRT 4.4.0 SEE BELOW! # + log_level = 1 + log_filters="1:qemu 3:remote 4:event 3:util.json 3:rpc" + log_outputs="1:file:/var/log/libvirt/libvirtd.log" + + + # PREFERRED SETTINGS AFTER LIBVIRT 4.4.0 # + log_filters="3:remote 4:event 3:util.json 3:rpc 1:*" + log_outputs="1:file:/var/log/libvirt/libvirtd.log"
You should have the code block marker on a separate line according to https://libvirt.org/styleguide.html#code-blocks. That also makes it possible to replicate the original layout of the page, where each set of variables lived in its own box: * find & replace, or set these variables: :: # LEGACY SETTINGS PRIOR LIBVIRT 4.4.0 SEE BELOW! # log_level = 1 log_filters="1:qemu 3:remote 4:event 3:util.json 3:rpc" log_outputs="1:file:/var/log/libvirt/libvirtd.log" :: # PREFERRED SETTINGS AFTER LIBVIRT 4.4.0 # log_filters="3:remote 4:event 3:util.json 3:rpc 1:*" log_outputs="1:file:/var/log/libvirt/libvirtd.log"
+In the config variables above, we have set logging level to 1 (debug level), +set some filters (to filter out noise), e.g. from rpc only warnings (=level 3) +and above will be reported. The logs are saved into +``/var/log/libvirt/libvirtd.log``. Since libvirt *4.4.0* log filters
Bold text looks **like this**, not *like this*, in reStructuredText. Unless you did that on purpose, in which case why not drop the markup for the version number altogether? :) [...]
+In order to change this set, run the same command as root, this time with your own set of filters:: + + ## LEGACY APPROACH ENUMERATING ALL THE DESIRED MODULES ## + # virt-admin daemon-log-filters "1:util 1:libvirt 1:storage 1:network 1:nodedev 1:qemu" + + ## CURRENT APPROACH USING SHELL GLOBBING ## + # virt-admin daemon-log-filters "3:remote 4:util.json 4:rpc 1:*"
These are two separate boxes in the original as well. [...]
+Prerequisites +------------- + +In cases where you want to see details of what is happening, you need to have +debugging symbols installed, at least for the package you are trying to debug. +Although having debugging symbols for all dependent libraries is usually +helpful as well. Usually ``gdb`` will tell you what you need to do in order to +get the proper data to your machine when you run it with a binary. + +=== Example: ===
You forgot to convert this into a reStructuredText section title. More specifically, it's a subsection of "Prerequisites", so it should look like Example ~~~~~~~ [...]
+When the package is installed, we can break on main and run until then (gdb's +command ``start`` is perfect for this):: + + # gdb $(which libvirtd) + GNU gdb (GDB) Fedora 8.2-6.fc29 + ... + Reading symbols from /usr/sbin/libvirtd...Reading symbols from /usr/lib/debug/usr/sbin/libvirtd-4.7.0-1.fc29.i386.debug...done. + done. + (gdb) start + Temporary breakpoint 1 at 0x18fc0: file remote/remote_daemon.c, line 1030. + Starting program: /usr/sbin/libvirtd + Missing separate debuginfos, use: dnf debuginfo-install glibc-2.28-26.fc29.i686 + Missing separate debuginfo for /lib/libvirt-lxc.so.0 + Try: dnf --enablerepo='*debug*' install /usr/lib/debug/.build-id/4d/16496b686ec54ca4201bd769b04293f6c756b3.debug + Missing separate debuginfo for /lib/libvirt-qemu.so.0 + Try: dnf --enablerepo='*debug*' install /usr/lib/debug/.build-id/ea/91d5346bd3e265ffb12ae641ca93643443e6e7.debug + Missing separate debuginfo for /lib/libvirt.so.0 + Try: dnf --enablerepo='*debug*' install /usr/lib/debug/.build-id/02/af3a96fc6227ed5e3a447344bcbb672bde14ba.debug + ... + Temporary breakpoint 1, main (argc=1, argv=0xbffff614) at remote/remote_daemon.c:1030 + 1030 int main(int argc, char **argv) { + Missing separate debuginfos, use: dnf debuginfo-install audit-libs-3.0-0.5.20181218gitbdb72c0.fc29.i686 avahi-libs-0.7-16.fc29.i686 brotli-1.0.5-1.fc29.i686 cyrus-sasl-lib-2.1.27-0.3rc7.fc29.i686 dbus-libs-1.12.12-1.fc29.i686 device-mapper-libs-1.02.154-1.fc29.i686 gmp-6.1.2-9.fc29.i686 gnutls-3.6.6-1.fc29.i686 keyutils-libs-1.5.10-8.fc29.i686 krb5-libs-1.16.1-25.fc29.i686 libacl-2.2.53-2.fc29.i686 libattr-2.4.48-3.fc29.i686 libblkid-2.32.1-1.fc29.i686 libcap-2.25-12.fc29.i686 libcap-ng-0.7.9-5.fc29.i686 libcom_err-1.44.4-1.fc29.i686 libcurl-7.61.1-10.fc29.i686 libffi-3.1-18.fc29.i686 libgcrypt-1.8.4-1.fc29.i686 libidn2-2.1.1a-1.fc29.i686 libmount-2.32.1-1.fc29.i686 libnghttp2-1.34.0-1.fc29.i686 libnl3-3.4.0-6.fc29.i686 libpsl-0.20.2-5.fc29.i686 libselinux-2.8-6.fc29.i686 libsepol-2.8-3.fc29.i686 libssh-0.8.7-1.fc29.i686 libssh2-1.8.1-1.fc29.i686 libtirpc-1.1.4-2.rc2.fc29.i686 libunistring-0.9.10-4.fc29.i686 libuuid-2.32.1-1.fc29.i686 libwsman1-2.6.5-8.fc29.i686 libxcrypt-4.4.4-2 .fc29.i686 libxml2-2.9.8-5.fc29.i686 lz4-libs-1.8.3-1.fc29.i686 numactl-libs-2.0.12-1.fc29.i686 openldap-2.4.46-10.fc29.i686 openssl-libs-1.1.1b-3.fc29.i686 p11-kit-0.23.15-2.fc29.i686 pcre2-10.32-8.fc29.i686 xz-libs-5.2.4-3.fc29.i686 yajl-2.1.0-11.fc29.i686 zlib-1.2.11-14.fc29.i686
Wow, this one breaks the page layout pretty horribly :D We will probably want to snip it or wrap it somehow. Let's leave that for a second pass, though. [...]
+This command will attach to currently running libvirtd process and run ``t a a +bt f``, which is short for ``thread apply all backtrace full``, feel free to +combine with ``sudo`` for users. If you are using this for virsh, or any other +binary which might have multiple processes running, then make sure you supply +the right pid for the ``-p`` option. For more info, read below about how to +automate gdb.
This should be a link, but you need to tweak the text a bit for it to work: something like For more info, read the section about `automating gdb`_ below. will do the trick. [...]
+* **setup your own** -- you can do one of these things: + + * set the ulimit for the service (depends on your init system) and look for + the file that gets created + * set kernel.core_pattern using sysctl to a command (rather than a filename + template) that gets ran with each core dump. This one does not need any + ulimit setting, but you need to know what to specify there.
Perhaps outside of the scope of your conversion, but I think that "kernel.core_pattern" should be enclosed in ``s.
+Automating gdb +-------------- + +When you need more specific behaviour from gdb, you can automate that, but for +multiline commands you need an input redirection or execute them from the file. + + +Multiline example +-----------------
This, as well as the next section, is also a subsection of "Automating gdb", and should be marked accordingly. [...]
+Daemon needs to be reloaded to know about this file:: + + # systemctl daemon-reload + +We also need to make sure that the file we created will be readable by the +service. DAC should be fine, SELinux might get tricky. By placing the file +under ``/var/lib/libvirt`` this should be readable by both the init system and +the libvirt daemon, but we need to make sure it has a proper context:: + + # restorecon -F /var/lib/libvirt/gdbabortscript /etc/systemd/system/libvirtd.service.d/override.conf
These two code blocks are indented by only two spaces instead of the standard three. We should probably figure out a way to check this kind of stuff automatically, because I got many wrong as well O:-) -- Andrea Bolognani / Red Hat / Virtualization