Add documentation on minimum supported versions (#1344)

DEVELOPING.md

@@ -48,7 +48,7 @@ Note that in the test, we can access `pwndbg` library code like `pwndbg.gdblib.r
 
 # Linting
 
-The `lint.sh` script runs `isort`, `black`, `flake8`, and `shfmt`. `isort` and `black` are able to automatically fix any issues they detect, and you can enable this by running `./lint.sh -f`. You can find the configuration files for these tools in `setup.cfg` and `pyproject.toml`.
+The `lint.sh` script runs `isort`, `black`, `flake8`, `shfmt`, and `vermin`. `isort` and `black` are able to automatically fix any issues they detect, and you can enable this by running `./lint.sh -f`. You can find the configuration files for these tools in `setup.cfg` and `pyproject.toml`.
 
 When submitting a PR, the CI job defined in `.github/workflows/lint.yml` will verify that running `./lint.sh` succeeds, otherwise the job will fail and we won't be able to merge your PR.
 
@@ -59,6 +59,14 @@ You can optionally set the contents of `.git/hooks/pre-push` to the following if
 ./lint.sh || exit 1
 ```
 
+# Minimum Supported Versions
+
+Our goal is to fully support all Ubuntu LTS releases that have not reach end-of-life, with support for other platforms on a best-effort basis. Currently that means all code should work on Ubuntu 18.04, 20.04, and 22.04 with GDB 8.1 and later. This means that the minimum supported Python version is 3.6.9, and we cannot use any newer Python features unless those features are backported to this minimum version.
+
+Note that while all code should run without errors on these supported LTS versions, it's fine if older versions don't support all of the features of newer versions, as long as this is handled correctly and this information is shown to the user. For example, we may make use of some GDB APIs in newer versions that we aren't able to provide alternative implementations for in older versions, and so in these cases we should inform the user that the functionality can't be provided due to the version of GDB.
+
+The `lint.sh` script described in the previous section runs [`vermin`](https://github.com/netromdk/vermin) to ensure that our code does not use any features that aren't supported on Python 3.6.
+
 # Random developer notes
 
 Feel free to update the list below!

README.md

@@ -30,7 +30,7 @@ Pwndbg exists not only to replace all of its predecessors, but also to have a cl
 
 ## How?
 
-Installation is straightforward.  Pwndbg is best supported on Ubuntu 18.04 with GDB 7.11, and Ubuntu 20.04 with GDB 8.1.
+Installation is straightforward:
 
 ```shell
 git clone https://github.com/pwndbg/pwndbg
@@ -38,6 +38,8 @@ cd pwndbg
 ./setup.sh
 ```
 
+Pwndbg is supported on Ubuntu 18.04, 20.04, and 22.04 with GDB 8.1 and later. We do not test on any older versions of Ubuntu, so `pwndbg` may not work on these versions. We may accept pull rrequests fixing issues in older versions on a case by case basis, please discuss this with us on [Discord](https://discord.gg/x47DssnGwm) first. You can also always checkout an older version of `pwndbg` from around the time the Ubuntu version you're interested in was still supported by Canonical, or you can attempt to build a newer version of GDB from source.
+
 Other Linux distributions are also supported via `setup.sh`, including:
 
 * Debian-based OSes (via apt-get)