Cinnamonを搭載したDebian10（Buster）：ハードウェアレンダリングなし
デスクトップ環境としてCinnamonを使用してDebianBusterをインストールしました。ログイン後、Cinnamonはデスクトップに警告を表示し、ソフトウェアレンダリングモードで実行されていることを示します。これはトラブルシューティングの目的でのみ推奨されます。 .xsession-errorsログは同じことを言います（以下を参照）。シナモンはウェイランドの下を走っていると思います。
システムには専用のグラフィックカードがありません。 Intel I7 9700K CP プロセッサグラフィックスが代わりに使用されます。
Cinnamonをハードウェアアクセラレーションで実行するにはどうすればよいですか？
システム
CPU: Intel I7 9700K (Coffee Lake)
Mainboard: MSI Z390 A-Pro (latest BIOS)
SSD: Samsung SSD 970 Evo Plus at the board's M.2 connector
OS: Debian 10 (Buster)
カーネル
# uname -a
Linux 4.19.0-5-AMD64 #1 SMP Debian 4.19.37-5+deb10u2 (2019-08-08) x86_64 GNU/Linux
グラフィックドライバ/ライブラリ
i965-va-driver/stable,now 2.3.0+dfsg1-1 AMD64 [installed,automatic]
intel-media-va-driver/stable,now 18.4.1+dfsg1-1 AMD64 [installed,automatic]
libva-drm2/stable,now 2.4.0-1 AMD64 [installed,automatic]
libva-x11-2/stable,now 2.4.0-1 AMD64 [installed,automatic]
libva2/stable,now 2.4.0-1 AMD64 [installed,automatic]
mesa-va-drivers/stable,now 18.3.6-2 AMD64 [installed,automatic]
va-driver-all/stable,now 2.4.0-1 AMD64 [installed,automatic]
.xsession-errorsからの抜粋
Cinnamon warning: Software rendering detected: llvmpipe (LLVM 7.0, 256 bits)
Cjs-Message: 06:07:12.080: JS LOG: About to start Cinnamon
Cjs-Message: 06:07:12.080: JS LOG: ACTIVATING SOFTWARE RENDERING
Cjs-Message: 06:07:12.080: JS LOG: [LookingGlass/error] Cinnamon Software Rendering mode enabled
** Message: 06:07:12.092: nemo-desktop: session is not cinnamon (checked XDG_SESSION_DESKTOP,DESKTOP_SESSION environment variables.) Applying default behavior
Cjs-Message: 06:07:12.125: JS LOG: [LookingGlass/info] Cinnamon.AppSystem.get_default() started in 44 ms
Cjs-Message: 06:07:12.128: JS LOG: [LookingGlass/info] loading default theme
Cinnamon warning: Log level 128: posix_spawn avoided (fd close requested)
Cjs-Message: 06:07:12.187: JS LOG: [LookingGlass/info] PlacesManager: Updating devices
St-Message: 06:07:12.188: cogl npot texture sizes SUPPORTED
Cjs-Message: 06:07:12.193: JS LOG: [LookingGlass/info] loaded at Thu Aug 29 2019 06:07:12 GMT+0000 (UTC)
Cjs-Message: 06:07:12.193: JS LOG: Cinnamon started at Thu Aug 29 2019 06:07:12 GMT+0000 (UTC)
Cjs-Message: 06:07:12.210: JS LOG: [LookingGlass/info] ExtensionSystem started in 2 ms
Cjs-Message: 06:07:12.210: JS LOG: [LookingGlass/info] DeskletManager started in 0 ms
Cjs-Message: 06:07:12.210: JS LOG: [LookingGlass/info] SearchProviderManager started in 0 ms
openGL version 3.3 detected (GL3 Cogl Driver)
MetaSyncRing disabled: couldn't find required GL extensions, or the minimum safe openGL version was not met
Cjs-Message: 06:07:12.255: JS LOG: [LookingGlass/info] Loaded applet [email protected] in 16 ms
Cjs-Message: 06:07:12.259: JS LOG: [LookingGlass/info] Loaded applet [email protected] in 4 ms
Cjs-Message: 06:07:12.278: JS LOG: [LookingGlass/info] Loaded applet [email protected] in 16 ms
Cjs-Message: 06:07:12.282: JS LOG: [LookingGlass/info] Role locked: notifications
Cjs-Message: 06:07:12.291: JS LOG: [LookingGlass/info] Loaded applet [email protected] in 12 ms
Cjs-Message: 06:07:12.304: JS LOG: [LookingGlass/info] Loaded applet [email protected] in 14 ms
Cjs-Message: 06:07:12.321: JS LOG: [LookingGlass/info] Loaded applet [email protected] in 16 ms
Cjs-Message: 06:07:12.339: JS LOG: [LookingGlass/info] Role locked: panellauncher
Cjs-Message: 06:07:12.341: JS LOG: [LookingGlass/info] Loaded applet [email protected] in 20 ms
Cjs-Message: 06:07:12.352: JS LOG: [LookingGlass/info] Loaded applet [email protected] in 12 ms
Cjs-Message: 06:07:12.360: JS LOG: [LookingGlass/info] Loaded applet [email protected] in 8 ms
Cjs-Message: 06:07:12.407: JS LOG: [LookingGlass/info] Loaded applet [email protected] in 46 ms
Cjs-Message: 06:07:12.437: JS LOG: [LookingGlass/info] Loaded applet [email protected] in 30 ms
Cjs-Message: 06:07:12.682: JS LOG: [LookingGlass/info] Loaded applet [email protected] in 246 ms
Cjs-Message: 06:07:12.683: JS LOG: [LookingGlass/info] AppletManager started in 490 ms
Cjs-Message: 06:07:12.683: JS LOG: [LookingGlass/info] AppletManager started in 490 ms
Cjs-Message: 06:07:12.717: JS LOG: [LookingGlass/info] Cinnamon took 636 ms to start
Lsmodの出力
Module Size Used by
snd_hda_codec_hdmi 57344 0
snd_hda_codec_realtek 122880 1
snd_hda_codec_generic 86016 1 snd_hda_codec_realtek
Fuse 122880 3
intel_rapl 24576 0
x86_pkg_temp_thermal 16384 0
i915 1728512 0
intel_powerclamp 16384 0
coretemp 16384 0
kvm_intel 245760 0
drm_kms_helper 200704 1 i915
kvm 724992 1 kvm_intel
drm 483328 2 drm_kms_helper,i915
i2c_algo_bit 16384 1 i915
irqbypass 16384 1 kvm
snd_hda_intel 45056 2
snd_hda_codec 151552 4 snd_hda_codec_generic,snd_hda_codec_hdmi,snd_hda_intel,snd_hda_codec_realtek
crct10dif_pclmul 16384 0
crc32_pclmul 16384 0
snd_hda_core 94208 5 snd_hda_codec_generic,snd_hda_codec_hdmi,snd_hda_intel,snd_hda_codec,snd_hda_codec_realtek
ghash_clmulni_intel 16384 0
snd_hwdep 16384 1 snd_hda_codec
intel_cstate 16384 0
snd_pcm 114688 4 snd_hda_codec_hdmi,snd_hda_intel,snd_hda_codec,snd_hda_core
snd_timer 36864 1 snd_pcm
intel_uncore 135168 0
snd 94208 12 snd_hda_codec_generic,snd_hda_codec_hdmi,snd_hwdep,snd_hda_intel,snd_hda_codec,snd_hda_codec_realtek,snd_timer,snd_pcm
mei_me 45056 0
iTCO_wdt 16384 0
sg 36864 0
wmi_bmof 16384 0
intel_rapl_perf 16384 0
mei 118784 1 mei_me
soundcore 16384 1 snd
pcspkr 16384 0
iTCO_vendor_support 16384 1 iTCO_wdt
intel_pch_thermal 16384 0
acpi_pad 24576 0
evdev 28672 9
acpi_tad 16384 0
pcc_cpufreq 16384 0
parport_pc 32768 1
ppdev 20480 0
lp 20480 0
parport 57344 3 parport_pc,lp,ppdev
ip_tables 28672 0
x_tables 45056 1 ip_tables
autofs4 49152 2
ext4 733184 3
crc16 16384 1 ext4
mbcache 16384 1 ext4
jbd2 122880 1 ext4
crc32c_generic 16384 0
fscrypto 32768 1 ext4
ecb 16384 0
hid_generic 16384 0
usbhid 57344 0
hid 135168 2 usbhid,hid_generic
sd_mod 61440 4
crc32c_intel 24576 5
mxm_wmi 16384 0
xhci_pci 16384 0
nvme 36864 1
e1000e 282624 0
ahci 40960 3
xhci_hcd 266240 1 xhci_pci
libahci 40960 1 ahci
libata 270336 2 libahci,ahci
aesni_intel 200704 0
usbcore 290816 3 xhci_hcd,usbhid,xhci_pci
scsi_mod 245760 3 sd_mod,libata,sg
aes_x86_64 20480 1 aesni_intel
crypto_simd 16384 1 aesni_intel
cryptd 28672 3 crypto_simd,ghash_clmulni_intel,aesni_intel
nvme_core 81920 3 nvme
glue_helper 16384 1 aesni_intel
i2c_i801 28672 0
usb_common 16384 1 usbcore
thermal 20480 0
fan 16384 0
wmi 28672 2 wmi_bmof,mxm_wmi
video 45056 1 i915
button 16384 0
参照： https://www.intel.com/content/www/us/en/products/processors/core/i7-processors/i7-9700k.html
別のマザーボードを試した後、私はついに問題を解決することができました。
必要な変更は、Debian BusterのデフォルトのLinuxカーネル（4.19.x）をDebian Busterバックポート（5.3.x）から最新のカーネルに更新することだけのようです。
その更新後、ソフトウェアレンダリング警告メッセージはそれ以上のアクションなしで消えました。