Comment 2 for bug 1819443

Thanks for your rapid response.

1. They are pre-compiled DTB files contained in the linux-modules-* packages where 'do_dtbs' is set (currently ARMHF and ARM64).

$ dpkg -l | grep linux-modules
ii linux-modules-4.15.0-29-generic 4.15.0-29.31 arm64 Linux kernel extra modules for version 4.15.0 on ARMv8 SMP
ii linux-modules-4.15.0-34-generic 4.15.0-34.37 arm64 Linux kernel extra modules for version 4.15.0 on ARMv8 SMP
ii linux-modules-4.15.0-43-generic 4.15.0-43.46 arm64 Linux kernel extra modules for version 4.15.0 on ARMv8 SMP
ii linux-modules-extra-4.15.0-29-generic 4.15.0-29.31 arm64 Linux kernel extra modules for version 4.15.0 on ARMv8 SMP
ii linux-modules-extra-4.15.0-34-generic 4.15.0-34.37 arm64 Linux kernel extra modules for version 4.15.0 on ARMv8 SMP
ii linux-modules-extra-4.15.0-43-generic 4.15.0-43.46 arm64 Linux kernel extra modules for version 4.15.0 on ARMv8 SMP

$ apt download linux-modules-4.15.0-43-generic
Get:1 http://gb.ports.ubuntu.com/ubuntu-ports bionic-updates/main arm64 linux-modules-4.15.0-43-generic arm64 4.15.0-43.46 [11.9 MB]
Fetched 11.9 MB in 5s (2,490 kB/s)

$ dpkg-deb -R linux-modules-4.15.0-43-generic_4.15.0-43.46_arm64.deb unpack

$ find . | grep dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/lg/lg1312-ref.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/lg/lg1313-ref.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/freescale/fsl-ls2080a-simu.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/freescale/fsl-ls1012a-rdb.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/freescale/fsl-ls1088a-rdb.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/freescale/fsl-ls2080a-rdb.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/freescale/fsl-ls1043a-qds.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/freescale/fsl-ls1012a-qds.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/freescale/fsl-ls2088a-rdb.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/freescale/fsl-ls1046a-qds.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/freescale/fsl-ls2080a-qds.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/freescale/fsl-ls1088a-qds.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/freescale/fsl-ls2088a-qds.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/freescale/fsl-ls1043a-rdb.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/freescale/fsl-ls1046a-rdb.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/freescale/fsl-ls1012a-frdm.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/apm/apm-merlin.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/apm/apm-mustang.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/amd/amd-overdrive-rev-b0.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/amd/amd-overdrive-rev-b1.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/amd/amd-overdrive.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/amd/husky.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/sprd/sp9860g-1h10.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/sprd/sc9836-openphone.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/actions/s900-bubblegum-96.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/hisilicon/hi3660-hikey960.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/hisilicon/hip06-d03.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/hisilicon/hi3798cv200-poplar.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/hisilicon/hip07-d05.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/hisilicon/hi6220-hikey.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/hisilicon/hip05-d02.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/altera/socfpga_stratix10_socdk.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/allwinner/sun50i-h5-orangepi-zero-plus2.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/allwinner/sun50i-a64-bananapi-m64.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/allwinner/sun50i-a64-olinuxino.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/allwinner/sun50i-a64-pine64.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/allwinner/sun50i-a64-sopine-baseboard.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/allwinner/sun50i-h5-orangepi-pc2.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/allwinner/sun50i-h5-orangepi-prime.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/allwinner/sun50i-a64-orangepi-win.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/allwinner/sun50i-a64-nanopi-a64.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/allwinner/sun50i-h5-nanopi-neo-plus2.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/allwinner/sun50i-a64-pine64-plus.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/allwinner/sun50i-h5-nanopi-neo2.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/xilinx/zynqmp-ep108.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/cavium/thunder2-99xx.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/cavium/thunder-88xx.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/realtek/rtd1295-mele-v9.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/realtek/rtd1295-probox2-ava.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/realtek/rtd1295-zidoo-x9s.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/broadcom/northstar2/ns2-svk.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/broadcom/northstar2/ns2-xmc.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/broadcom/bcm2837-rpi-3-b.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/broadcom/stingray/bcm958742t.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/broadcom/stingray/bcm958742k.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/qcom/msm8994-angler-rev-101.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/qcom/msm8992-bullhead-rev-101.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/qcom/apq8096-db820c.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/qcom/msm8996-mtp.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/qcom/apq8016-sbc.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/qcom/msm8916-mtp.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/qcom/ipq8074-hk01.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/arm/juno-r1.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/arm/vexpress-v2f-1xv7-ca53x2.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/arm/foundation-v8-gicv3.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/arm/foundation-v8-psci.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/arm/juno.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/arm/rtsm_ve-aemv8a.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/arm/foundation-v8.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/arm/foundation-v8-gicv3-psci.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/arm/juno-r2.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/renesas/r8a7795-salvator-x.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/renesas/r8a7795-h3ulcb-kf.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/renesas/r8a7796-m3ulcb-kf.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/renesas/r8a7795-es1-h3ulcb.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/renesas/r8a7796-m3ulcb.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/renesas/r8a77995-draak.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/renesas/r8a7795-es1-h3ulcb-kf.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/renesas/r8a7795-h3ulcb.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/renesas/r8a77970-eagle.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/renesas/r8a7796-salvator-x.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/renesas/r8a7795-es1-salvator-x.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/renesas/r8a7795-salvator-xs.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/marvell/berlin4ct-stb.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/marvell/berlin4ct-dmp.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/mediatek/mt6755-evb.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/mediatek/mt8173-evb.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/mediatek/mt7622-rfb1.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/mediatek/mt6797-evb.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/mediatek/mt2712-evb.dtb
./unpack/lib/firmware/4.15.0-43-generic/device-tree/mediatek/mt6795-evb.dtb

2. I haven't looked for a partition. I thought the installer was ISO 9660 which is RO.

3. Trying them all is not a good idea. They should all boot to various stages of borkage/levels of functionality. The user should really select the correct one for the platform.