Updating a system without support for 3d to run the unity shell
When updating your system with Update Manager, you will see a warning if your machine does not have 3D support for running the unity desktop environment. This could happen for several reasons:
- Outdated hardware not providing required level of OpenGL support
- Too new hardware without driver support yet
- Obscure hardware without 3d support
- Virtual machines
- Binary drivers required but not installed
If you choose to continue anyway, Ubuntu will try to run using software rendering (via LLVMpipe). While llvmpipe is pretty good on modern CPUs, if your video card is old your CPU is likely old too, and it may result in unusable performance.
Alternatives may include sticking with an old ubuntu release or switching to one of the lighter weight derivatives or Debian. For 12.04 and 12.10, ubuntu-classic (no effects) is also a feasible option. To do this, install the gnome-session-fallback package, and then on the login screen click the gear icon and select "Ubuntu-classic (no effects)".