James has written to the OpenChrome mailing list and has sent along a patch that provides this readied TTM (Translation Table Maps) and GEM (Graphics Execution Manager) support for the limited DRM (Direct Rendering Manager) driver living within the Linux kernel.
This patch is set to go against David Airlie's drm-next branch of the kernel. This patch that plugs-in the new memory management back-end will still work with existing OpenChrome UMS (user-space mode-setting) installations. The driver works, but there's a few problems left to be solved, such as a kernel oops when unloading this DRM module. It can also be tried with the KMS branch to benefit from kernel mode-setting.
The patch can currently be found here. In just about one month, with one developer getting TTM/GEM support hooked in, it's sad that VIA couldn't get it done back when they had Linux plans in 2009 and still the TTM/GEM support was months out or that it couldn't be tackled by any of the OpenChrome community developers. Let's see though if this patch will be fully ironed out and make it into the Linux 2.6.39 kernel or another release in the near future.