lspci -vvnnk

01:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] RV620 LE [Radeon HD 3450 AGP] [1002:95c6] (prog-if 00 [VGA controller])
	Subsystem: Hightech Information System Ltd. RV620 LE [Radeon HD 3450 AGP] [1787:0028]
	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 (2000ns min), Cache Line Size: 32 bytes
	Interrupt: pin A routed to IRQ 11
	NUMA node: 0
	Region 0: Memory at e0000000 (32-bit, prefetchable) [size=256M]
	Region 1: I/O ports at e000 [size=256]
	Region 2: Memory at fbf00000 (32-bit, non-prefetchable) [size=64K]
	Expansion ROM at 000c0000 [disabled] [size=128K]
	Capabilities: [50] Power Management version 3
		Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
		Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
	Capabilities: [58] AGP version 3.0
		Status: RQ=256 Iso- ArqSz=0 Cal=0 SBA+ ITACoh- GART64- HTrans- 64bit- FW+ AGP3+ Rate=x4,x8
		Command: RQ=1 ArqSz=0 Cal=0 SBA+ AGP- GART64- 64bit- FW- Rate=<none>
	Kernel modules: radeon

glxheads

  Display:     0x560bb61ef920
  Window:      0xc00002
  Context:     0x560bb6209930
  GL_VERSION:  3.1 Mesa 18.3.6
  GL_VENDOR:   VMware, Inc.
  GL_RENDERER: llvmpipe (LLVM 7.0, 128 bits)

dmesg

[    8.005273] [drm] radeon kernel modesetting enabled.
[    8.010735] [drm:radeon_pci_probe [radeon]] *ERROR* radeon kernel modesetting for R600 or later requires firmware installed
[    8.010818] See https://wiki.debian.org/Firmware for information about missing firmware