Comment 59 for bug 1316035

Short version: kernel module driver "mgag200" did the trick for me. In kernel config, it is represented by CONFIG_DRM_MGAG200.
http://cateee.net/lkddb/web-lkddb/DRM_MGAG200.html

I found a bug that is relevant to this one: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1642470 It says that the kernel module "mgag200" was blacklisted from kernels due to this bug: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1042903 I tried manually compiling the driver as a module, adding it to a kernel and it worked.

I had problems with MGA G200e [Pilot] ServerEngines (SEP1) card. I tried Zoltán's X.org regression hack, I also tried using a recompiled up-to-date mga_drv.so, the library in xserver-xorg-video-mga, where the maintainers claim to support G200e chip (https://cgit.freedesktop.org/xorg/driver/xf86-video-mga/, commits from July 2016). Nothing worked. I am, however, just an intermediate user, so I might have made a mistake somewhere. I also do not know the difference between a kernel driver, X.org driver, and how they interact together and how they are used. Therefore I will trust someone more knowledgeable to put this all together, and I am just going to describe what I did to make it work :-)

As a reference, I did a fresh install of Linux Mint 18.1 MATE, where the GPU was unclaimed:

$ uname -a
Linux rack3test 4.4.0-66-generic #87-Ubuntu SMP Fri Mar 3 15:29:05 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
$ sudo lshw -c display
  *-display UNCLAIMED
       description: VGA compatible controller
       product: MGA G200e [Pilot] ServerEngines (SEP1)
       vendor: Matrox Electronics Systems Ltd.
       physical id: 0
       bus info: pci@0000:02:00.0
       version: 05
       width: 32 bits
       clock: 33MHz
       capabilities: pm pciexpress msi vga_controller bus_master cap_list
       configuration: latency=0
       resources: memory:c2000000-c2ffffff memory:c1010000-c1013fff memory:c0800000-c0ffffff memory:c1000000-c100ffff

Then I tried two approaches, both worked.

1. the easier way is to compile and install just the module mgag200. I downloaded the sources and headers for the current kernel, compiled and installed the module, and then added it in the initramfs image. Then, after reboot, it worked. Here are the resources I used:

http://askubuntu.com/questions/168279/how-do-i-build-a-single-in-tree-kernel-module
http://askubuntu.com/questions/676707/how-to-load-a-module-in-initrd

In the first one, do not forget to use your kernel version and the path to the module (drivers/gpu/drm/mgag200). Also it is probably more convenient to use "$ make menuconfig" instead of editing the .config file with vi (you need the ncurses package though). In the menu, find Graphics Drivers --> Graphics Support --> Kernel modesetting driver for MGA G200 server engines, and enable it as a module. When updating initramfs, it might be necessary to specify the kernel version, for example $ update-initramfs -u -k 4.4.0-66-generic. If you have multiple kernels, the command will tell you which initramfs it updated.

The result after a reboot:
$ uname -a
Linux rack3test 4.4.0-66-generic #87-Ubuntu SMP Fri Mar 3 15:29:05 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
$ sudo lshw -c display
  *-display
       description: VGA compatible controller
       product: MGA G200e [Pilot] ServerEngines (SEP1)
       vendor: Matrox Electronics Systems Ltd.
       physical id: 0
       bus info: pci@0000:02:00.0
       version: 05
       width: 32 bits
       clock: 33MHz
       capabilities: pm pciexpress msi vga_controller bus_master cap_list rom
       configuration: driver=mgag200 latency=0
       resources: irq:16 memory:c2000000-c2ffffff memory:c1010000-c1013fff memory:c0800000-c0ffffff memory:c1000000-c100ffff

2. Second way is building a new kernel, which is much longer; unfortunately, I tried it first :-) I downloaded the current stable kernel sources from kernel.org, version 4.10.1. Then I used the existing kernel config file for 4.4.0-66-generic, updated it with default choices to 4.10.1 and enabled CONFIG_DRM_MGAG200 as a module. I compiled the whole kernel and installed it, the new driver "mgag200" loads automatically and it works.

I used Linux Mint 18.1 for testing, but the installed system is Mint 17.2. I tried compiling the kernel module there for kernel version 3.16.0-38-generic, but after enabling module mgag200 with modprobe, the screen turned black and monitor went into sleep mode. I had to switch to tty1 and reboot. After reboot, the module mgag200 was visible in lsmod, but probably not active and the GPU was still unclaimed with no hardware acceleration.

Maybe I did something wrong, but it is possible that the mgag200 module helps only with newer kernels.

You can check whether your device is recognized by this driver in the first link in this comment. Numeric ID (vendor, device) can be displayed by running $ sudo lshw -c display -numeric, it will be in square brackets under "product".

If anyone tries this, please let me know if it worked.