-[1] Please notice that lenny is an unsupported release within Debian nowadays.
-grml-debootstrap can handle the release but you really should not use lenny
-anymore unless you really know what you are doing. Choose Debian 7.0 (wheezy) or
-something newer instead.
+[1] Please notice that releases like lenny, squeeze, wheezy, jessie, stretch and buster are unsupported releases within Debian nowadays.
+grml-debootstrap can handle the releases but you really should not use them
+anymore unless you really know what you are doing.
+Choose the current Debian stable version instead.
+See https://wiki.debian.org/DebianReleases for the list of supported releases.
+
+Notice that you need to specify a specific mirror providing old releases, the default (http://deb.debian.org/debian) doesn't provide them any longer.
+Set the mirror to e.g. http://archive.debian.org/debian/ if you don't have your own Debian mirror.
+
+Older releases might also fail to install when running on top of recent kernel versions,
+throwing segfaults during debootstrap. This can be identified by the following messages inside kernel log (check with 'dmesg'):
+
+ dpkg[...] vsyscall attempted with vsyscall=none ip:[...]
+ dpkg[...]: segfault at [...]
+
+To work around this issue boot your system with the kernel boot option 'vsyscall=emulate'.
+
+You also need to specify a filesystem that's supported by lenny, e.g.
+'--filesystem ext3' since grml-debootstrap's current default (ext4) isn't
+supported by lenny.
+
+Also when debootstrapping lenny on a live system with a kernel version
+like "3.16-1-grml-amd64" lenny's libc will fail to install with:
+
+ [...]
+ /var/lib/dpkg/tmp.ci/preinst: line 265: [: 3.16-1-grml-amd64: integery expression expected
+ /var/lib/dpkg/tmp.ci/preinst: line 231: 3.16-1-grml-amd64: syntax error: invalid arithemtic operator (error token is ".16-1-grml-amd64")
+ dpkg: error processing /var/cache/apt/archives/libc6_2.7-18lenny7_amd64.deb (--install):
+ [....]