I tried but failed to get the kernel going.

I downloaded 
linux-headers-4.12.0-041200_4.12.0-041200.201707022031_all.deb
linux-headers-4.12.0-041200-generic_4.12.0-041200.201707022031_amd64.deb
linux-image-4.12.0-041200-generic_4.12.0-041200.201707022031_amd64.deb

Then I ran sudo dpkg -i *.deb from the folder containing the debs and got a lot of error messages:
10:37 PM ~/Dropbox/Mainline $ sudo dpkg -i *.deb
[sudo] password for vasa1: 
Selecting previously unselected package linux-headers-4.12.0-041200.
(Reading database ... 301085 files and directories currently installed.)
Preparing to unpack linux-headers-4.12.0-041200_4.12.0-041200.201707022031_all.deb ...
Unpacking linux-headers-4.12.0-041200 (4.12.0-041200.201707022031) ...
Selecting previously unselected package linux-headers-4.12.0-041200-generic.
Preparing to unpack linux-headers-4.12.0-041200-generic_4.12.0-041200.201707022031_amd64.deb ...
Unpacking linux-headers-4.12.0-041200-generic (4.12.0-041200.201707022031) ...
Selecting previously unselected package linux-image-4.12.0-041200-generic.
Preparing to unpack linux-image-4.12.0-041200-generic_4.12.0-041200.201707022031_amd64.deb ...
Done.
Unpacking linux-image-4.12.0-041200-generic (4.12.0-041200.201707022031) ...
Setting up linux-headers-4.12.0-041200 (4.12.0-041200.201707022031) ...
Setting up linux-headers-4.12.0-041200-generic (4.12.0-041200.201707022031) ...
Examining /etc/kernel/header_postinst.d.
run-parts: executing /etc/kernel/header_postinst.d/dkms 4.12.0-041200-generic /boot/vmlinuz-4.12.0-041200-generic
ERROR (dkms apport): kernel package linux-headers-4.12.0-041200-generic is not supported
Error! Bad return status for module build on kernel: 4.12.0-041200-generic (x86_64)
Consult /var/lib/dkms/ath9k-msi/1.0/build/make.log for more information.
Error!  The dkms.conf for this module includes a BUILD_EXCLUSIVE directive which
does not match this kernel/arch.  This indicates that it should not be built.
Error!  The dkms.conf for this module includes a BUILD_EXCLUSIVE directive which
does not match this kernel/arch.  This indicates that it should not be built.
ERROR (dkms apport): kernel package linux-headers-4.12.0-041200-generic is not supported
Error! Bad return status for module build on kernel: 4.12.0-041200-generic (x86_64)
Consult /var/lib/dkms/radeon-si/1a/build/make.log for more information.
Setting up linux-image-4.12.0-041200-generic (4.12.0-041200.201707022031) ...
Running depmod.
update-initramfs: deferring update (hook will be called later)
Examining /etc/kernel/postinst.d.
run-parts: executing /etc/kernel/postinst.d/apt-auto-removal 4.12.0-041200-generic /boot/vmlinuz-4.12.0-041200-generic
run-parts: executing /etc/kernel/postinst.d/dkms 4.12.0-041200-generic /boot/vmlinuz-4.12.0-041200-generic
ERROR (dkms apport): kernel package linux-headers-4.12.0-041200-generic is not supported
Error! Bad return status for module build on kernel: 4.12.0-041200-generic (x86_64)
Consult /var/lib/dkms/ath9k-msi/1.0/build/make.log for more information.
Error!  The dkms.conf for this module includes a BUILD_EXCLUSIVE directive which
does not match this kernel/arch.  This indicates that it should not be built.
Error!  The dkms.conf for this module includes a BUILD_EXCLUSIVE directive which
does not match this kernel/arch.  This indicates that it should not be built.
ERROR (dkms apport): kernel package linux-headers-4.12.0-041200-generic is not supported
Error! Bad return status for module build on kernel: 4.12.0-041200-generic (x86_64)
Consult /var/lib/dkms/radeon-si/1a/build/make.log for more information.
run-parts: executing /etc/kernel/postinst.d/initramfs-tools 4.12.0-041200-generic /boot/vmlinuz-4.12.0-041200-generic
update-initramfs: Generating /boot/initrd.img-4.12.0-041200-generic
run-parts: executing /etc/kernel/postinst.d/pm-utils 4.12.0-041200-generic /boot/vmlinuz-4.12.0-041200-generic
run-parts: executing /etc/kernel/postinst.d/unattended-upgrades 4.12.0-041200-generic /boot/vmlinuz-4.12.0-041200-generic
run-parts: executing /etc/kernel/postinst.d/update-notifier 4.12.0-041200-generic /boot/vmlinuz-4.12.0-041200-generic
run-parts: executing /etc/kernel/postinst.d/zz-update-grub 4.12.0-041200-generic /boot/vmlinuz-4.12.0-041200-generic
Generating grub configuration file ...
Warning: Setting GRUB_TIMEOUT to a non-zero value when GRUB_HIDDEN_TIMEOUT is set is no longer supported.
Found linux image: /boot/vmlinuz-4.12.0-041200-generic
Found initrd image: /boot/initrd.img-4.12.0-041200-generic
Found linux image: /boot/vmlinuz-4.4.0-83-generic
Found initrd image: /boot/initrd.img-4.4.0-83-generic
Found linux image: /boot/vmlinuz-4.4.0-81-generic
Found initrd image: /boot/initrd.img-4.4.0-81-generic
Adding boot menu entry for EFI firmware configuration
done
10:39 PM ~/Dropbox/Mainline $ 

All the same, I rebooted but didn't see 4.12 as a kernel option. So I leave things at that unless there are other suggestions.