I was looking into compiling the excellent PicoDrive, but its sources seem to be here and there and no generic Linux version exists.
It seems by all accounts that Megadrive/Genesis emulation under PPC Linux is a hopeless attempt: Dgen just crashes, Xmess doesn’t do any better, and up-to-date emulators, such as Gens/GS, don’t support the PPC platform (a generic Z80 core is apparently under construction). This time exceptionally in English – I thought this might benefit some fellow PPC users abroad, too. PPC Linux and Sega Megadrive/Genesis emulation