No KMS, works only with the framebuffer driver which has to be set in Xorg's config.

lspci -vvnnk

01:00.0 VGA compatible controller [0300]: Matrox Electronics Systems Ltd. MGA G400/G450 [102b:0525] (rev 85) (prog-if 00 [VGA controller])
	Subsystem: Matrox Electronics Systems Ltd. Millennium G450 DVI [102b:23c3]
	Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
	Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 64 (4000ns min, 8000ns max), Cache Line Size: 64 bytes
	Interrupt: pin A routed to IRQ 10
	Region 0: Memory at fc000000 (32-bit, prefetchable) [size=32M]
	Region 1: Memory at fb200000 (32-bit, non-prefetchable) [size=16K]
	Region 2: Memory at fa800000 (32-bit, non-prefetchable) [size=8M]
	[virtual] Expansion ROM at 000c0000 [disabled] [size=128K]
	Capabilities: [dc] Power Management version 2
		Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
		Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
	Capabilities: [f0] AGP version 2.0
		Status: RQ=32 Iso- ArqSz=0 Cal=0 SBA+ ITACoh- GART64- HTrans- 64bit- FW- AGP3- Rate=x1,x2,x4
		Command: RQ=32 ArqSz=0 Cal=0 SBA+ AGP+ GART64- 64bit- FW- Rate=x1
	Kernel driver in use: matrox_w1
	Kernel modules: matrox_w1

glxheads

  Display:     0x2063d20
  Window:      0xc00002
  Context:     0x2077ab0
  GL_VERSION:  3.1 Mesa 19.0.5
  GL_VENDOR:   VMware, Inc.
  GL_RENDERER: llvmpipe (LLVM 8.0, 128 bits)