Dom0 is isolated from domUs. DomUs can access only a few interfaces, such as Xen, device backends (in the dom0 kernel and in other VMs, such as the NetVM), and Qubes tools (gui-daemon, qrexec-daemon, etc.).
These components are [security-critical](/doc/security-critical-code/), and we provide updates for all of them (when necessary), regardless of the support status of the base distribution.
It is the responsibility of each distribution to clearly notify its users in advance of its own EOL dates, and it is users' responsibility to heed these notices by upgrading to supported releases.
As a courtesy to Qubes users, we attempt to pass along any upstream EOL notices we receive for officially-supported templates, but our ability to do this reliably is dependent on the upstream distribution's practices.
If a distribution provides a mailing list similar to [qubes-announce](/support/#qubes-announce), which allows us to receive only very important, infrequent messages, including EOL announcements, we are much more likely to be able to pass along EOL notices to Qubes users reliably.
Qubes users can always check the EOL status of an upstream release on the upstream distribution's website (see [Fedora EOL](https://fedoraproject.org/wiki/End_of_life) and [Debian Releases](https://wiki.debian.org/DebianReleases)).
<sup>\*</sup> Although Debian 9 has reached regular EOL and is now in [LTS](https://wiki.debian.org/LTS), we continue to support it for Qubes R4.0.
This is a *temporary* exception to our [policy](#note-on-debian-support) of ending Qubes support at each Debian release's *regular* (not LTS) EOL date, since this policy was introduced after the release of Qubes R4.0.
In Qubes R4.1 and beyond, Qubes support for each Debian release will end when that release reaches regular EOL and will not extend into LTS.
### Note on Debian support
Debian releases have two EOL dates: regular and [long-term support (LTS)](https://wiki.debian.org/LTS).
See [Debian Production Releases](https://wiki.debian.org/DebianReleases#Production_Releases) for a chart that illustrates this.
Qubes support ends at the *regular* EOL date, *not* the LTS EOL date, unless a specific exception has been made.
This policy requires Whonix template users to stay reasonably close to the cutting edge by upgrading to new stable versions of Qubes OS and Whonix templates within a month of their respective releases.
* One month after a new stable version of Qubes OS is released, Whonix templates will no longer be supported on any older version of Qubes OS.
This means that users who wish to continue using Whonix templates on Qubes must always upgrade to the latest stable Qubes OS version within one month of its release.
* One month after new stable versions of Whonix templates are released, older versions of Whonix templates will no longer be supported.
This means that users who wish to continue using Whonix templates on Qubes must always upgrade to the latest stable Whonix template versions within one month of their release.
