Allow override of the trusty system vm packages

This will be overridden by desktop emulator configs to switch out the
trusty vm thas is loaded.

Due to the nature of lazy expansion in Make, the `+=` does *not*
immediately expand the `?=`. This can be observed by running `make test`
with the following Makefile:

```
p = a b
x ?= x y z
p += $(x)
x := c d

test:
	@echo $(p)
```

Bug: 398934069
Test: launch_cvd unaffected
Change-Id: I631b6da2e8db2b4b5c66ecff37d0bfedf07fc1aa
1 file changed
tree: ebc505b3e62163935d267bf0e21267abfe82d69f
  1. android/
  2. build/
  3. docs/
  4. guest/
  5. libs/
  6. microfuchsia/
  7. tests/
  8. .clang-format
  9. .gitignore
  10. Android.bp
  11. dice_for_avf_guest.cddl
  12. OWNERS
  13. PREUPLOAD.cfg
  14. README.md
  15. rustfmt.toml
  16. TEST_MAPPING
README.md

Android Virtualization Framework (AVF)

Android Virtualization Framework (AVF) provides secure and private execution environments for executing code. AVF is ideal for security-oriented use cases that require stronger isolation assurances over those offered by Android’s app sandbox.

Visit our public doc site to learn more about what AVF is, what it is for, and how it is structured. This repository contains source code for userspace components of AVF.

If you want a quick start, see the getting started guideline and follow the steps there.

For in-depth explanations about individual topics and components, visit the following links.

AVF components:

AVF APIs:

How-Tos: