mirror of
https://github.com/libvirt/libvirt.git
synced 2026-09-03 20:53:04 -05:00
Laine Stump
0a867cd895
iptables and ip6tables have had a "-w" commandline option to grab a systemwide lock that prevents two iptables invocations from modifying the iptables chains since 2013 (upstream commit 93587a04 in iptables-1.4.20). Similarly, ebtables has had a "--concurrent" commandline option for the same purpose since 2011 (in the upstream ebtables commit f9b4bcb93, which was present in ebtables-2.0.10.4). Libvirt added code to conditionally use the commandline option for iptables/ip6tables in upstream commitba95426d6f(libvirt-1.2.0, November 2013), and for ebtables in upstream commitdc33e6e4a5(libvirt-1.2.11, November 2014) (the latter actually *re*-added the locking for iptables/ip6tables, as it had accidentally been removed during a refactor of firewall code in the interim). I say "conditionally" because a check was made during firewall module initialization that tried executing a test command with the -w/--concurrent option, and only continued using it for actual commands if that test command completed successfully. At the time the code was added this was a reasonable thing to do, as it had been less than a year since introduction of -w to iptables, so many distros supported by libvirt were still using iptables (and possibly even ebtables) versions too old to have the new commandline options. It is now 2020, and as far as I can discern from repology.org (and manually examining a RHEL7.9 system), every version of every distro that is supported by libvirt now uses new enough versions of both iptables and ebtables that they all have support for -w/--concurrent. That means we can finally remove the conditional code and simply always use them. Signed-off-by: Laine Stump <laine@redhat.com> Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
libvirt library code README
===========================
The directory provides the bulk of the libvirt codebase. Everything
except for the libvirtd daemon and client tools. The build uses a
large number of libtool convenience libraries - one for each child
directory, and then links them together for the final libvirt.so,
although some bits get linked directly to libvirtd daemon instead.
The files directly in this directory are supporting the public API
entry points & data structures.
There are two core shared modules to be aware of:
* util/ - a collection of shared APIs that can be used by any
code. This directory is always in the include path
for all things built
* conf/ - APIs for parsing / manipulating all the official XML
files used by the public API. This directory is only
in the include path for driver implementation modules
* vmx/ - VMware VMX config handling (used by esx/ and vmware/)
Then there are the hypervisor implementations:
* bhyve - bhyve - The BSD Hypervisor
* esx/ - VMware ESX and GSX support using vSphere API over SOAP
* hyperv/ - Microsoft Hyper-V support using WinRM
* lxc/ - Linux Native Containers
* openvz/ - OpenVZ containers using cli tools
* qemu/ - QEMU / KVM using qemu CLI/monitor
* remote/ - Generic libvirt native RPC client
* test/ - A "mock" driver for testing
* vbox/ - Virtual Box using native API
* vmware/ - VMware Workstation and Player using the vmrun tool
* xen/ - Xen using hypercalls, XenD SEXPR & XenStore
Finally some secondary drivers that are shared for several HVs.
Currently these are used by LXC, OpenVZ, QEMU and Xen drivers.
The ESX, Hyper-V, Remote, Test & VirtualBox drivers all
implement the secondary drivers directly
* cpu/ - CPU feature management
* interface/ - Host network interface management
* network/ - Virtual NAT networking
* nwfilter/ - Network traffic filtering rules
* node_device/ - Host device enumeration
* secret/ - Secret management
* security/ - Mandatory access control drivers
* storage/ - Storage management drivers
Since both the hypervisor and secondary drivers can be built as
dlopen()able modules, it is *FORBIDDEN* to have build dependencies
between these directories. Drivers are only allowed to depend on
the public API, and the internal APIs in the util/ and conf/
directories