NOTE: Haven't tested with Debian/Ubuntu yet, but on Devuan, the
linux-libc-dev deb package is not needed, just the other three: linux-image,
linux-headers, and linux-firmware-image.
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Pls. check if these are the most recent:
linux-deb-grsec-current
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For warnings and other details, pls. see some older README, e.g.
the pre-meltdown-spectre era 4.9.72-grsecunoff 2017-12-28
This 4.9.74-grsecunoff of 2018-02-04 has:
*) the retpoline patch applied, the most important ingredient otherwise missing
for AMD processor based systems:
https://github.com/HacKurx/public-sharing/blob/master/retpoline_for_unofficial_grsec-4.9.74.patch
*) it (likely) has the backported patch applied that enables loading of the new
amd64-microcode with spectre vuln 2 mitigation (but I wasn't able to verify
this: couldn't load the new amd64-microcode on my ADM64 processor-based
systems, details in the minipli grsecunoff issue #26 linked below; confusing: I
couldn't load new amd64-microcode with the latest available Debian/Devuan
spectre/meltdown aware kernel either
Meltdown protection currently still unavailable in grsecunoff, as of this
writing (meaning Intel proc based systems remain unprotected from meltdown).
See discussions at
https://github.com/minipli/linux-unofficial_grsec/issues/26 and around.
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You can compile your own unofficial-grsecurity-hardened kernel by
following my:
grsec-dev1-compile script guide.
Make sure you also read:
Grsecurity/Pax installation on Devuan GNU/Linux
which is my home distro
or if you're with the mother distro, then try:
Grsecurity/Pax installation on Debian GNU/Linux
Regards!