Download kernel from kernel.org & extract tarball.
Set up and apply patches.
mkdir patches
# put the patch to patches/
quilt new patches/file.patch
quilt pop -a && quilt push -a
Put the config file and and update config.
cp /boot/config-6.12.12-amd64 .config
make olddefconfig
Disable dbgsym compilation.
scripts/config --disable DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
scripts/config --disable DEBUG_INFO_DWARF5
# For old kernels:
scripts/config --disable DEBUG_INFO
Disable Canonical certificates.
scripts/config --set-str SYSTEM_TRUSTED_KEYS ""
scripts/config --set-str SYSTEM_REVOCATION_KEYS ""
Compile with ccache.
PATH=/usr/lib/ccache:${PATH} CCACHE_COMPRESS=true make bindeb-pkg -j$(nproc)