In June, 2007 some great developers started maintaining Gens for Linux again. They have taken all of the patches from this page and integrated them, with lots of other good fixes, into the main codebase. You can find this all at the SourceForge page.
While in the process of setting up MythGame for some Sega Genesis roms I have, I ran into some problems. The first issue is that there aren't any well maintained Genesis emulators for Linux. Just for your reference there seem to be three main ones:
Of these, it seems like Gens has the best compatibility and features. Also, there seem to be quite a number of people who have created patches to add bits of functionality here and there. I have also found deficiencies with Gens, so I have created a patch for those features, and merged it with features from others around the web. Below you can find all of these patches and patched versions of Gens for your compiling fun!
There are two main code bases for Gens, the 2.12b-rc3 available on the SourceForge site (under Gens WIP Linux), and the rc3.5-opengl branch created by wah_wah_69. If you want more details about the opengl branch, check out the Gentoo Forums Thread. I have mirrored both archives here for ease of use.
These two patches are actually a combination of some of my own work, plus some very useful patches from other Gens users. Here are the patches I combined from others:
The GCC4 patch from Avuton Olrich simply makes Gens compile wil GCC4, however, I am not sure if this code will compile with GCC3.
Brian Hearn's work fixed the "--fs" command line parameter, fixed loading of roms from the command line, and added the "--quickexit" parameter to allow for exiting the emulator with the ESC key.
Stepher Cofer changed Gens so that it will remember that last directory you loaded a rom from (when using the GUI).
I fixed joystick support so that you can use joysticks with 6 axes (previously only 2 axes were supported). I also changed it so that the first 6 joysticks on a system would be used with Gens (previously it would only interface with the first 2). In addition, all of the command line parameters are now documented so when you run "gens --help" you actually know what everything does!
To differentiate this modified version of Gens, I have changed the sdl version in the usage description and about dialog to "Gens for Linux 2.12-mythgame". The opengl version is now "Gens for Linux 2.12-mythgame-opengl". Here are the two patches:
To apply these patches, copy the patch file to gens-mythgame or gens-mythgame-opengl (depending on your version), cd to that directory and then run the command:
patch -p1 < gens-rc3_to_mythgame.patch
or
patch -p1 < gens-rc3.5-opengl_to_mythgame-opengl.patch
Finally, here are the source code bases with the patches already applied. These will be of the most help to those who aren't comfortable running patch.